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.

metadata/migrations/0024_create_dashboard_permissions.sql

@@ -1,7 +1,7 @@
 -- Additive-only per-resource grant: lets a specific user exceed their
 -- tenant-baseline role on one dashboard (e.g. an Editor granted Admin on
 -- a dashboard they don't own). No deny-overrides -- named non-goal in
--- /docs/phase-4-rbac-design.md and CLAUDE.md's Phase 4 exit criteria.
+-- /docs/phase-4-rbac-design.md and PROJECT-SPEC.md's Phase 4 exit criteria.
 CREATE TABLE IF NOT EXISTS dashboard_permissions
 (
     id           UUID PRIMARY KEY,