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/http/dto/issue-token.dto.ts

@@ -1,35 +1,48 @@
+import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
 import { IsIn, IsNotEmpty, IsString, IsUrl, ValidateIf } from 'class-validator';
 
+/** OAuth2 token request (RFC 6749), as JSON or application/x-www-form-urlencoded. */
 export class IssueTokenDto {
+  @ApiProperty({ enum: ['authorization_code', 'password', 'refresh_token'] })
   @IsIn(['authorization_code', 'password', 'refresh_token'])
   grant_type!: 'authorization_code' | 'password' | 'refresh_token';
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'authorization_code')
   @IsString()
   @IsNotEmpty()
+  @ApiPropertyOptional({
+    description: 'authorization_code: code returned by Pireon',
+  })
   code?: string;
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'authorization_code')
   @IsString()
   @IsNotEmpty()
+  @ApiPropertyOptional({ description: 'authorization_code: PKCE verifier' })
   code_verifier?: string;
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'authorization_code')
   @IsUrl({ require_tld: false })
+  @ApiPropertyOptional({
+    description: 'authorization_code: redirect URI used to authorize',
+  })
   redirect_uri?: string;
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'password')
   @IsString()
   @IsNotEmpty()
+  @ApiPropertyOptional({ description: 'password: Pireon email' })
   username?: string;
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'password')
   @IsString()
   @IsNotEmpty()
+  @ApiPropertyOptional({ description: 'password: Pireon password' })
   password?: string;
 
   @ValidateIf((dto: IssueTokenDto) => dto.grant_type === 'refresh_token')
   @IsString()
   @IsNotEmpty()
+  @ApiPropertyOptional({ description: 'refresh_token' })
   refresh_token?: string;
 }