Rebrand: Sentry -> Cairn OBS

Full rebrand across cosmetic branding, code identifiers, and
infrastructure/data-plane naming, using the supplied Cairn OBS logo
package. Cosmetic: favicon/logo swap (also closes a stale license-audit
finding -- the old favicon was SvelteKit's unreplaced scaffold logo),
new centered welcome landing page, larger/legible sidebar logo, page
titles, CLAUDE.md/README/docs prose.

Code identifiers: Go module path github.com/sentry/sentry ->
github.com/cairnobs/cairnobs across all 13 modules and ~91 files (protoc
regenerated); Rust crates sentry-agent/sentry-parser/sentry-search ->
cairnobs-*; CLI sentryctl -> cairnobsctl; Terraform provider fully
renamed (sentry_dashboard etc. -> cairnobs_dashboard, provider type,
env vars); every session/auth cookie name; agent config paths and
Windows service identity.

Deliberately preserved: the gRPC wire protocol's protobuf packages
(sentry.logs.v1, sentry.agent.v1) and their Go import directory
(proto/sentry/...) -- renaming the wire-level package would break every
currently-deployed agent binary (confirmed two real hosts, including
mail.inbuxa.com, are actively streaming through this exact contract)
until rebuilt and redeployed in lockstep with an ingest cutover. Only
the Go module path wrapping the generated code changes.

Infrastructure: every docker-compose container name (root and three
component-level compose files); the Helm chart (directory, Chart.yaml,
named-template helpers, all templates, values.yaml image repos);
Kubernetes Operator (CRD group sentry.io -> cairnobs.io, both CRD YAML
files, Go identifiers, RBAC markers); the coupled enterprise/tenantcrd
package. Caught and fixed real path-coupling bugs along the way: the
Helm chart's search/ingest volume mounts and the dev-only-credential
detection constant vs. docker-compose.yml's literal values had to move
together or a security warning would have silently stopped firing.

Data plane: Postgres database sentry_metadata -> cairnobs_metadata and
role sentry -> cairnobs; ClickHouse database sentry -> cairnobs; Kafka
topic sentry.logs.raw -> cairnobs.logs.raw and its consumer groups.
Source-level defaults, docker-compose.yml, and every migrate.sh/
provision script default updated together; already-applied migration
files left untouched per this repo's immutable-migration convention.

Verified at every layer: all 13 Go modules build/vet/test clean, both
Rust workspaces (agent, search) build/clippy/test clean, npm run check/
build clean, docker compose config validates on all four compose files.
Live-verified against a real docker stack multiple times through this
work, including a final fresh-volume run confirming the actual renamed
Postgres database/role, ClickHouse database, and Kafka topic all work
end to end with a real login and query, zero console errors.

docs/phase-1-runbook.md

@@ -128,14 +128,14 @@ compile time), same requirement as the Linux build.
 ### C2. Get mTLS certs onto the Windows host
 
 Copy `hack/dev-certs/out/{ca,client,client-key}.pem` from wherever you
-ran `generate.sh` to `C:\ProgramData\SentryAgent\` on the Windows host
+ran `generate.sh` to `C:\ProgramData\CairnObsAgent\` on the Windows host
 (create the directory first). Same dev-only certs Phase 0's Linux agent
 uses — the CA doesn't care what platform the client is on, only that the
 client cert was signed by it.
 
 ### C3. Config
 
-Create `C:\ProgramData\SentryAgent\agent.toml`:
+Create `C:\ProgramData\CairnObsAgent\agent.toml`:
 
 ```toml
 [source]
@@ -155,7 +155,7 @@ needed (same note as Phase 0's runbook's troubleshooting section).
 
 ```powershell
 $env:RUST_LOG="info"
-.\sentry-agent.exe --config C:\ProgramData\SentryAgent\agent.toml
+.\cairnobs-agent.exe --config C:\ProgramData\CairnObsAgent\agent.toml
 ```
 
 Confirms the Event Log source and mTLS connection work before adding the
@@ -167,7 +167,7 @@ diagnose here than after wrapping it in a service.
 From another PowerShell window (or Event Viewer):
 
 ```powershell
-eventcreate /T INFORMATION /ID 1 /L APPLICATION /SO "SentryTest" /D "phase1 windows verification line"
+eventcreate /T INFORMATION /ID 1 /L APPLICATION /SO "CairnObsTest" /D "phase1 windows verification line"
 ```
 
 Then check both query paths, same pattern as A2.
@@ -175,11 +175,11 @@ Then check both query paths, same pattern as A2.
 ### C6. Install as a service
 
 ```powershell
-.\sentry-agent.exe install
-sc.exe start SentryAgent
+.\cairnobs-agent.exe install
+sc.exe start CairnObsAgent
 ```
 
-Verify it's running (`sc.exe query SentryAgent`) and generate another
+Verify it's running (`sc.exe query CairnObsAgent`) and generate another
 test event to confirm it's still flowing through while running as a
 service, not just in the foreground. **Known gap:** no console under the
 SCM means `tracing`'s log output currently has nowhere to go — see
@@ -188,8 +188,8 @@ something goes wrong here, you're debugging blind until that's
 addressed; C4's foreground run is where to diagnose real problems.
 
 ```powershell
-sc.exe stop SentryAgent
-.\sentry-agent.exe uninstall
+sc.exe stop CairnObsAgent
+.\cairnobs-agent.exe uninstall
 ```
 
 ### C7 (optional). ETW