Rename the project spec and update every reference to it

The charter file carried a tool-specific name while being the repository's own
document: mission, non-negotiable constraints, the pinned stack, repo
conventions and phase status, cited as authority by thirty files across the
agent, api, deploy, docs, search and terraform trees.

PROJECT-SPEC.md says what it is. All 42 references are updated in the same
commit, including the relative link in docs/status.md, so nothing points at a
filename that no longer exists.

enterprise/README.md

@@ -206,7 +206,7 @@ below) and Tantivy (`/search/README.md`'s "Per-tenant indices" section
 routing (does traffic actually reach `enterprise-api` instead of
 `api`), now a single-flag choice in both `deploy/helm/cairnobs` and
 `docker-compose.yml` (`enterprise.enabled` / `COMPOSE_PROFILES`), see
-CLAUDE.md.
+PROJECT-SPEC.md.
 
 ## Ingest tenant identity
 

enterprise/cmd/enterprise-api/main.go

@@ -20,7 +20,7 @@
 // Both Helm (deploy/helm/cairnobs/templates/api.yaml vs
 // enterprise-api.yaml) and docker-compose.yml (COMPOSE_PROFILES) now
 // make this the deployment-topology choice, not just a binary sitting
-// unused alongside api's -- see this repo's CLAUDE.md. `search`'s write
+// unused alongside api's -- see this repo's PROJECT-SPEC.md. `search`'s write
 // side (ingest, and by extension the Redpanda consumer search itself
 // runs) is still not tenant-aware -- see enterprise/internal/searchclient
 // and search/src/registry.rs's doc comments, and

enterprise/internal/tenantcrd/tenantcrd.go

@@ -1,6 +1,6 @@
 // Package tenantcrd syncs enterprise-api -provision-tenant's real
 // provisioning result into the Tenant CRD (deploy/operator/api/
-// v1alpha1) -- the "lightweight unification" named in CLAUDE.md's "two
+// v1alpha1) -- the "lightweight unification" named in PROJECT-SPEC.md's "two
 // independent provisioning mechanisms" gap: -provision-tenant stays the
 // sole real actor (rbacstore + tenantprovision.ProvisionClickHouse, see
 // runProvisionTenant's doc comment in cmd/enterprise-api/main.go); this