feat(api): REST API with OpenAPI for other apps, behind Pireon OAuth

A REST adapter next to GraphQL (presenters/http) that calls the same
application services, so validation, permissions and domain errors are the
same: projects (members, board, stats, activity), issues (search, workflow,
assignee, release, links, comments, history), comments, releases and users.
Projects and issues can be addressed by id or key (WEB, WEB-12).

- Swagger UI at /api/docs, document at /api/docs-json and apps/api/openapi.json
  (rewritten by `nx serve api`, like schema.gql) for client generation.
- Every route but health/auth/webhook needs a Pireon token: the document
  declares Pireon OAuth2 (authorization code + PKCE, password) through the
  /api/auth/token proxy, and a bearer scheme for apps with their own client.
- configureApp() shares main.ts setup with the e2e, which now also covers REST.
- SWAGGER_ENABLED / OPENAPI_FILE config; docs 03/05 and library READMEs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/identity/presenters/src/lib/auth/auth.decorators.ts

@@ -1,8 +1,10 @@
 import {
   ExecutionContext,
   SetMetadata,
+  applyDecorators,
   createParamDecorator,
 } from '@nestjs/common';
+import { ApiBearerAuth, ApiOAuth2 } from '@nestjs/swagger';
 import { getAuthRequest } from './auth-request';
 
 export const IS_PUBLIC = 'identity:isPublic';
@@ -25,3 +27,15 @@ export const AccessToken = createParamDecorator(
   (_: unknown, context: ExecutionContext) =>
     getAuthRequest(context).accessToken,
 );
+
+/** OpenAPI security schemes (declared in apps/api/src/app/openapi.ts). */
+export const PIREON_OAUTH = 'pireon-oauth';
+export const PIREON_BEARER = 'pireon';
+
+/**
+ * Documents that the endpoints need a Pireon access token: obtained through
+ * Pireon's OAuth (authorization code + PKCE, or password) or sent as a bearer
+ * token by an app that already has one. Enforced by the global AuthGuard.
+ */
+export const ApiPireonAuth = () =>
+  applyDecorators(ApiOAuth2([], PIREON_OAUTH), ApiBearerAuth(PIREON_BEARER));