chore: generate portal-shell and portal-bff apps per ADR-0004 / ADR-0005

Add the @nx/angular, @nx/nest, @nx/vite, @nx/eslint plugins, then
generate the two apps. Adjust the empty-template tsconfig.base.json
to be Angular-compatible (drop project references and customConditions
that the empty-template defaults to but Angular doesn't support; keep
the strict-TS extensions from ADR-0004).

apps/portal-shell (Angular 21):
- standalone APIs, routing, SCSS, esbuild
- vitest-angular as unitTestRunner, playwright for e2e
- strict mode
- tags scope:portal-shell, type:app
- app.config.ts wired with provideZonelessChangeDetection() per
  ADR-0004 (Angular 21 + Nx 22 generates without zone.js by default)

apps/portal-bff (NestJS 11):
- Express adapter (default per ADR-0005)
- Jest as unitTestRunner
- tags scope:portal-bff, type:app
- main.ts wired with a global ValidationPipe configured
  whitelist + forbidNonWhitelisted + transform per ADR-0005
- Phase-2 security additions (helmet, CORS, sessions, CSRF, rate
  limit, auth guards, error filter) deferred to their respective
  ADRs - placeholder comment in main.ts

Workspace dependencies: class-validator + class-transformer added
(required by NestJS ValidationPipe at runtime). Nx-generated
.gitignore additions (.angular, __screenshots__) merged into ours.
.vscode/extensions.json and launch.json added by Nx are kept (do not
override our existing settings.json).

tsconfig.base.json

@@ -1,24 +1,28 @@
 {
   "compilerOptions": {
-    "composite": true,
-    "declarationMap": true,
-    "emitDeclarationOnly": true,
+    "rootDir": ".",
+    "baseUrl": ".",
+    "paths": {},
+    "sourceMap": true,
+    "declaration": false,
     "importHelpers": true,
     "isolatedModules": true,
-    "lib": ["es2022"],
-    "module": "nodenext",
-    "moduleResolution": "nodenext",
-    "noEmitOnError": true,
+    "lib": ["es2022", "dom"],
+    "module": "esnext",
+    "moduleResolution": "bundler",
+    "target": "es2022",
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true,
+    "useDefineForClassFields": false,
     "noFallthroughCasesInSwitch": true,
     "noImplicitOverride": true,
     "noImplicitReturns": true,
     "noUnusedLocals": true,
     "skipLibCheck": true,
+    "skipDefaultLibCheck": true,
     "strict": true,
     "noUncheckedIndexedAccess": true,
     "exactOptionalPropertyTypes": true,
-    "noPropertyAccessFromIndexSignature": true,
-    "target": "es2022",
-    "customConditions": ["apf-portal"]
+    "noPropertyAccessFromIndexSignature": true
   }
 }