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/modules/api-keys/api-keys.module.ts

@@ -1,12 +1,13 @@
 import { Global, Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { ApiKey } from '../../entities/api-key.entity';
+import { License } from '../../entities/license.entity';
 import { ApiKeysController } from './api-keys.controller';
 import { ApiKeysService } from './api-keys.service';
 
 @Global()
 @Module({
-  imports: [TypeOrmModule.forFeature([ApiKey])],
+  imports: [TypeOrmModule.forFeature([ApiKey, License])],
   controllers: [ApiKeysController],
   providers: [ApiKeysService],
   exports: [ApiKeysService],