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.

search/README.md

@@ -44,7 +44,7 @@ a second copy of the row.
 `src/registry.rs`'s `IndexRegistry` searches: empty resolves to the
 single default index every deployment already had; a non-empty value
 opens (on first use) a dedicated index under `TENANTS_INDEX_PATH`
-(default `/var/lib/sentry-search/tenants/<tenant_id>`, matching
+(default `/var/lib/cairnobs-search/tenants/<tenant_id>`, matching
 `deploy/operator`'s and `enterprise/internal/rbacstore`'s existing path
 convention). `tenant_id` is set only by a trusted server-side caller
 (`enterprise/internal/searchclient`, from the authenticated request
@@ -109,7 +109,7 @@ discovered dynamically.
 
 Whatever Tantivy's own `QueryParser` supports against the `message`
 field: plain terms, `"exact phrase"` queries, and `foo*` wildcards. Not
-documented further here because it's Tantivy's syntax, not Sentry's — see
+documented further here because it's Tantivy's syntax, not Cairn OBS's — see
 [Tantivy's query parser docs](https://docs.rs/tantivy/latest/tantivy/query/struct.QueryParser.html)
 for the full grammar. No unified query language yet; that's Phase 2.
 
@@ -123,9 +123,9 @@ Environment variables (see `src/config.rs`):
 | `REDPANDA_BROKERS` | `localhost:9092` | Comma-separated broker list |
 | `REDPANDA_TOPIC` | `sentry.logs.raw` | Must match `/ingest`'s topic |
 | `REDPANDA_TOPIC_PARTITIONS` | `6` | Must match what `/transport/provision-topics.sh` created |
-| `INDEX_PATH` | `/var/lib/sentry-search/index` | Default (non-tenant) Tantivy index directory |
-| `TENANTS_INDEX_PATH` | `/var/lib/sentry-search/tenants` | Per-tenant index directories live under here, one subdirectory per tenant_id (Phase 4) |
-| `OFFSETS_PATH` | `/var/lib/sentry-search/offsets.json` | Offset tracking file |
+| `INDEX_PATH` | `/var/lib/cairnobs-search/index` | Default (non-tenant) Tantivy index directory |
+| `TENANTS_INDEX_PATH` | `/var/lib/cairnobs-search/tenants` | Per-tenant index directories live under here, one subdirectory per tenant_id (Phase 4) |
+| `OFFSETS_PATH` | `/var/lib/cairnobs-search/offsets.json` | Offset tracking file |
 | `COMMIT_INTERVAL_MS` | `2000` | How often buffered writes become searchable |
 | `ENTERPRISE_AUTH_URL` | (empty) | Enables `tenants::ActiveTenantTracker` -- empty means write-routing has no active-tenant gate, same as every deployment before Phase 4. Must be set together with `ENTERPRISE_AUTH_SERVICE_TOKEN` below, or `Config::load` fails |
 | `ENTERPRISE_AUTH_SERVICE_TOKEN` | (empty) | RoleService Bearer credential for `GET /internal/active-tenants`, minted via `enterprise-auth -mint-service-token search` |
@@ -166,5 +166,5 @@ unreachable server), not a fake HTTP client substituted in.
 
 ```sh
 # from the repo root, not search/
-docker build -f search/Dockerfile -t sentry-search .
+docker build -f search/Dockerfile -t cairnobs-search .
 ```