Unify the Tenant CRD with enterprise-api -provision-tenant (lightweight)

Closes a gap named across CLAUDE.md/docs/architecture.md/deploy/README.md
since early Phase 4: the operator's Tenant CRD and -provision-tenant
were two disconnected mechanisms. The operator's reconciler generated a
K8s Secret with a locally-generated random password that authenticated
against nothing (nothing ever called ClickHouse to create a matching
user), and unconditionally claimed status.phase=Active the moment a
Tenant object existed -- actively misleading, not just incomplete.

Two unification shapes were considered (surfaced to the user via
AskUserQuestion, given the real difference in blast radius): the
operator's reconcile loop becoming a second real actor (new Postgres +
ClickHouse admin credentials flowing into the K8s controller, plus real
reconcile-loop idempotency/retry design for an inherently one-shot
external side effect), or keeping -provision-tenant as the sole real
actor and having it also sync its result into the CRD. Went with the
lighter option.

enterprise/internal/tenantcrd (new): a Syncer using the K8s dynamic
client (unstructured.Unstructured + a GroupVersionResource, not
deploy/operator's typed Tenant struct -- avoids a cross-module Go
dependency between two independently-versioned modules for one type).
Upserts the Tenant object, creates/updates a Secret with the *real*
ClickHouse credentials owned by that Tenant via an OwnerReference, then
patches status.{clickHouseDatabaseName,clickHouseSecretRef,
tantivyIndexPath}. Idempotent and safe to retry: never rotates a
credential across a re-sync, never overwrites a pre-existing
spec.displayName a human/GitOps process set.

cmd/enterprise-api/main.go's runProvisionTenant calls Sync when
TENANT_CRD_NAMESPACE is set (empty = no-op, same shape as every other
optional dependency in this codebase). Its "already active" refusal is
now split: ClickHouse re-provisioning is still refused (rotating a live
credential would break every open connection for no benefit), but CR
sync alone is now retryable using the credentials already on file in
rbacstore -- needed for retrying a previously-failed sync, or
backfilling CR sync for a tenant provisioned before this existed.

deploy/operator's reconciler rewritten to match: it never claims
PhaseActive on its own initiative anymore, only once
status.ClickHouseDatabaseName is non-empty (the field -provision-tenant,
and only -provision-tenant, sets). Phase is now a pure function of
{spec.suspended, status.ClickHouseDatabaseName != ""} recomputed every
reconcile, not toggled in place -- fixes a related bug the old code
would have hit once suspension was involved: un-suspending an
already-provisioned tenant needs to return straight to Active, which
isn't derivable from "last observed phase was Suspended" alone. The
reconciler no longer creates or manages any Secret, dropped its
`secrets` RBAC grant entirely, and gained zero new dependencies.

Helm chart: enterprise-api gets its own ServiceAccount/Role/RoleBinding
(get/list/create tenants, get/update/patch tenants/status, get/create/
update secrets -- least-privilege, scoped to the release namespace, not
a ClusterRole) and a TENANT_CRD_NAMESPACE env var, both gated on
tenantOperator.enabled. tenant-operator's ClusterRole loses the
secrets grant it no longer needs.

Verified in this environment: enterprise/internal/tenantcrd's tests run
against k8s.io/client-go's fake dynamic + typed clientsets (real client
library, fake transport, no cluster needed); deploy/operator's rewritten
tenant_controller_test.go runs against controller-runtime's fake
client, including new regression tests for the "must not claim Active
without confirmation" and "un-suspending returns to Active, not
Provisioning" properties; helm template + parsing the rendered YAML
confirms the RBAC split renders exactly as designed under both
tenantOperator.enabled=true/false. Not verified: an actual
-provision-tenant run against a real cluster with the operator watching
(no live cluster in this environment, same disclosed limitation as the
rest of /deploy). Docs updated in lockstep: CLAUDE.md, docs/architecture.md,
deploy/README.md, deploy/helm/sentry/README.md (including a corrected
"Trying the two-tenant example" walkthrough), phase-4-runbook.md (new
§11), enterprise/README.md. Also fixed two unrelated stale claims found
along the way: docs/architecture.md still said docker-compose.yml ran
plain api unconditionally (fixed in an earlier commit, doc not updated
then), and enterprise-api's own main.go doc comment still said Helm/
docker-compose wiring wasn't built yet.

deploy/README.md

@@ -21,26 +21,43 @@ map of per-tenant ClickHouse connection pools via `internal/chrunner`;
 that's an explicit Phase 4 non-goal (see `/CLAUDE.md`). What it *does*
 add:
 
-- A `Tenant` CRD + controller that generates and manages one dedicated
-  ClickHouse credential Secret per tenant (`operator/internal/controller`).
+- A `Tenant` CRD + controller (`operator/internal/controller`) that
+  reflects real provisioning state onto `status.phase`/a `Ready`
+  condition, derived from whether `enterprise-api -provision-tenant` has
+  reported real ClickHouse provisioning.
 - A Helm chart that can install zero-or-more `Tenant` CRs
-  (`values.tenants`) alongside the rest of the stack, and — the newer
-  piece — swaps `api`'s Deployment for `enterprise-api`'s whenever
-  `enterprise.enabled` is true, so which query binary actually serves
-  traffic is no longer a separately-forgettable decision (see
-  `helm/sentry/README.md`'s "`api` vs `enterprise-api`" section).
+  (`values.tenants`) alongside the rest of the stack, and swaps `api`'s
+  Deployment for `enterprise-api`'s whenever `enterprise.enabled` is
+  true, so which query binary actually serves traffic is no longer a
+  separately-forgettable decision (see `helm/sentry/README.md`'s "`api`
+  vs `enterprise-api`" section).
 
-**Two still-separate mechanisms, not yet unified**: the Operator's
-`Tenant` CRD manages only the K8s-side credential Secret — it does not
-call ClickHouse (no `CREATE DATABASE`/`CREATE USER`/`GRANT`) or touch
-the Tantivy filesystem. `enterprise-api -provision-tenant=<id>` is what
-actually does that (`enterprise/internal/tenantprovision`, built and
-tested — see `/enterprise/README.md`), driven independently via
-`rbacstore`, not from the `Tenant` CRD's reconcile loop. A `Tenant`
-reaching `status.phase: Active` here means "this tenant has a K8s
-Secret," not "this tenant's ClickHouse database/grants exist" — running
-both mechanisms for the same tenant ID today requires two separate
-operator actions, named explicitly rather than implied to be one.
+**Now unified, in a deliberately lightweight way**: `enterprise-api
+-provision-tenant=<id>` stays the sole real actor — it's the only thing
+that calls ClickHouse (`CREATE DATABASE`/`CREATE USER`/`GRANT`, via
+`enterprise/internal/tenantprovision`) and writes `rbacstore`. What
+changed: once it succeeds, it also syncs the result into the `Tenant`
+CRD (`enterprise/internal/tenantcrd`) — creating the Secret with *real*
+credentials (the controller no longer generates a placeholder one that
+authenticated against nothing) and setting the status fields the
+controller reads to compute `Phase`/`Ready`. The controller itself
+gained no new credentials and still never touches ClickHouse/Postgres --
+it's a pure function of `spec.suspended` and whatever
+`-provision-tenant` has reported, never an independent second guess at
+"is this tenant really provisioned." A `Tenant` reaching
+`status.phase: Active` now means the same thing `rbacstore.tenants.
+status='active'` does, not two different claims — see
+`enterprise/internal/tenantcrd`'s and `operator/internal/controller/
+tenant_controller.go`'s doc comments for the full split, and
+`enterprise-api -provision-tenant`'s `TENANT_CRD_NAMESPACE` env var
+(set automatically by the Helm chart when `tenantOperator.enabled`) to
+turn this on. Deliberately not built: the operator's reconcile loop
+itself calling ClickHouse/rbacstore directly (a "full unification"
+option considered and set aside — it would give the operator two new
+credential sets and require real reconcile-loop idempotency design for
+an inherently one-shot external side effect, a bigger and riskier
+change than this repo's provisioning story needed to close the actual
+gap, which was two *disconnected* sources of truth, not two actors).
 
 ## Verification status -- read before trusting this against a real cluster
 
@@ -59,6 +76,15 @@ access was available to fetch these tools, but no cluster):
   (`internal/controller/tenant_controller_test.go`) -- real reconcile
   logic exercised, but not against a real apiserver (no `envtest`
   binaries available; see that test file's doc comment).
+- `enterprise/internal/tenantcrd` (the "lightweight unification"
+  half `-provision-tenant` runs): `go test` passes against
+  `k8s.io/client-go`'s fake dynamic and typed clientsets -- real client
+  library, fake transport, same shape as `enterprise/internal/
+  searchclient`'s in-process gRPC tests. What this doesn't prove: that
+  `sentry.io/v1alpha1.Tenant`'s real CRD schema (a real apiserver's
+  OpenAPI validation) accepts exactly what this package writes -- the
+  `helm template`/kubeconform check below covers the schema shape, not
+  a live write against it.
 - `deploy/operator/config/crd/sentry.io_tenants.yaml`: parsed with
   `sigs.k8s.io/yaml` + strict-unmarshaled into the real
   `k8s.io/apiextensions-apiserver` `CustomResourceDefinition` Go type --
@@ -76,7 +102,13 @@ access was available to fetch these tools, but no cluster):
   parsing the rendered YAML (not just eyeballing it): exactly one
   `Deployment`/`Service` named `sentry-api` renders in each mode, with
   the `enterprise.enabled: true` render using the `enterprise-api` image
-  and the default render using plain `api`'s.
+  and the default render using plain `api`'s. Also confirmed for the
+  `tenantOperator.enabled: true` case: `enterprise-api` gets its own
+  ServiceAccount/Role/RoleBinding (exactly `tenants`/`tenants/status`/
+  `secrets`, no more), `tenant-operator`'s own ClusterRole no longer
+  grants `secrets` at all, and `TENANT_CRD_NAMESPACE` is set on
+  `enterprise-api`'s container only when `tenantOperator.enabled` is
+  true.
 - Docker image builds (`operator/Dockerfile` and every other
   `Dockerfile` this chart references) were **not** verified in this
   session -- Docker's daemon wasn't reachable here either (see the