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/helm/sentry/values.yaml

@@ -165,9 +165,11 @@ enterprise:
     idpMetadataURL: ""
 
 # Installs deploy/operator (the Tenant CRD controller) alongside this
-# chart. Only meaningful when enterprise.enabled is also true --
-# gated on that, not a separate flag, since a Tenant CR with no
-# enterprise-auth deployed to consume its Secret has nothing to do.
+# chart. Only meaningful when enterprise.enabled is also true -- gated
+# on that, not a separate flag, since a Tenant CR with nothing to
+# reflect (see below) has nothing to do. Also turns on enterprise-api's
+# own Tenant-CRD-syncing permissions (a ServiceAccount/Role, and the
+# TENANT_CRD_NAMESPACE env var) -- see templates/enterprise-api.yaml.
 tenantOperator:
   enabled: false
   image:
@@ -176,11 +178,16 @@ tenantOperator:
   resources: {}
 
 # One entry per tenant to provision -- rendered as Tenant CRs
-# (templates/tenants.yaml), reconciled by the tenant-operator into a
-# per-tenant ClickHouse credential Secret. See
-# deploy/operator/internal/controller/tenant_controller.go's doc comment
-# for exactly what that does and doesn't set up. Empty by default; a
-# real two-tenant deployment (Phase 4's exit criteria) sets e.g.:
+# (templates/tenants.yaml), a declarative request an admin/GitOps
+# process makes. The operator (tenant-operator, above) only ever
+# *reflects* real state onto these objects (Phase/Conditions, derived
+# from what enterprise-api's `-provision-tenant` has reported) -- it's
+# `-provision-tenant` (run via `kubectl exec` into the enterprise-api
+# Pod), not the operator, that actually calls ClickHouse and writes the
+# credential Secret. See deploy/operator/internal/controller/
+# tenant_controller.go's and enterprise/internal/tenantcrd's doc
+# comments for the full split. Empty by default; a real two-tenant
+# deployment (Phase 4's exit criteria) sets e.g.:
 #   tenants:
 #     - name: acme
 #       displayName: "Acme Corp"