feat(auth): API-key authentication — corr_ bearer key acts as license owner

Closes the 'Public REST API' last mile: external callers authenticate with a
per-license API key instead of a JWT. Additive and zero-regression:

- JwtAuthGuard: a corr_-prefixed bearer token (or X-API-Key header) is
  validated via ApiKeysService.validateKey and sets request.user shaped like a
  JWT user, scoped to the key's license. JWTs are eyJ... and never collide with
  the corr_ prefix, so the existing JWT path is byte-for-byte unchanged.
- API-key calls act AS the license owner: validateKey now resolves
  license.owner_user_id so sub is a real UUID — any @CurrentUser/created_by FK
  insert works and attributes correctly. (ApiKeysModule gains the License repo.)
- PermissionsGuard: is_api_key principals get full access to their own license
  (always tenant-scoped). Future: scoped/read-only keys.

Backend tsc green. Untested at runtime (no local DB) — needs a curl smoke test
on Saturday's fresh stack before the roadmap item flips to shipped.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend-nest/src/common/guards/permissions.guard.ts

@@ -19,6 +19,11 @@ export class PermissionsGuard implements CanActivate {
     // Super admins bypass all permission checks
     if (user.is_super_admin) return true;
 
+    // API keys are full programmatic access to their own license (always
+    // tenant-scoped by license_id via @CurrentTenant). Granted here rather than
+    // enumerating every permission. Future: scoped/read-only keys.
+    if (user.is_api_key) return true;
+
     // Check permissions JSONB from role
     const permissions = user.permissions as Record<string, boolean> | undefined;
     if (!permissions) return false;