chore(deps): upgrade NestJS 10 -> 11 (#754) (#856)

Major version bump of the entire NestJS ecosystem, including required
transitive dependencies that the v11 peer dependency tree now mandates.

Framework
- @nestjs/common, core, platform-express, platform-socket.io,
  websockets, testing -> ^11.1.27
- @nestjs/cli -> ^11.0.23, @nestjs/schematics -> ^11.1.0
- @nestjs/passport -> ^11.0.5, @nestjs/config -> ^4.0.4
- @nestjs/schedule (kept ^6.1.3, already NestJS 11 compatible)
- @nestjs/swagger -> ^11.4.4
- @nestjs/cache-manager -> ^3.1.3

GraphQL/Apollo
- @nestjs/apollo -> ^13.4.2
- @nestjs/graphql -> ^13.4.2
- @apollo/server -> ^5.5.1 (forced peer upgrade from @nestjs/apollo@13)

Forced transitive deps (NestJS 11 peer requirements)
- @nestjs/platform-express@11 now requires express ^5.0.0
   -> express -> ^5.2.1, multer -> ^2.2.0,
      @types/express -> ^5.0.6, @types/multer -> ^2.0.0
- @nestjs/cache-manager@3 requires keyv >=5
   -> keyv -> ^5.6.0
- @nestjs/graphql@13 requires ts-morph at the consumer level for
  code-first schema generation -> ts-morph -> ^28.0.0

Runtime requirements
- engines.node: >=18.0.0 -> >=20.0.0 (NestJS 11 requires Node 20+)

Source-code adjustments
- src/app.module.ts: removed legacy `playground: true` from
  GraphQLModule.forRoot(...) because Apollo Server v5 (@apollo/server@5,
  peer dep of @nestjs/apollo@13) drops the classic GraphQL Playground in
  favour of Apollo Sandbox (default). Re-enabling the legacy plugin would
  resolve a peer-dep warning, but is unnecessary for this project.
- src/main.ts: bumped the runtime Node version guard from `>= 18` to
  `>= 20` so an old CI image fails fast instead of crashing inside
  NestFactory.create with an unhandled engine error. Also removed a
  duplicate `app.useGlobalPipes(new ValidationPipe(...))` call that was
  silently overridden by a later call (now a single pipe with
  `transformOptions.enableImplicitConversion: true`).

CI
- .github/workflows/ci.yml: all five `actions/setup-node` jobs bumped
  from `node-version: 18` to `node-version: 20` to match the new eng
  requirement.

Notes for reviewers
- npm install emits an ERESOLVE warning for
  `@apollo/server-plugin-landing-page-graphql-playground@4` (a
  transitive of @nestjs/apollo@13). It is resolved automatically and
  is harmless because `playground: true` was removed; the plugin is
  never loaded at runtime.
- `cache-manager-redis-store@^3.0.1` is kept for now. It is a cache-
  manager@5 store and is already incompatible with the cache-manager@7
  stack pre-upgrade, so changing it is out of scope for this PR.

Validation
- npm install: succeeds (auto-overrides playground peer warning)
- npm run build: passes (exit 0)
- npm test: 224 passed, 2 skipped, 0 failed across 34 suites (+ 1
  pre-existing skipped suite)

closes #754

Co-authored-by: goodness-cpu <goodness-cpu@users.noreply.github.com>
Co-authored-by: nanaf6203-bit <nanaf6203@gmail.com>

Author: goodness-cpu

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Setup Node.js
       uses: actions/setup-node@v3
       with:
-        node-version: '18'
+        node-version: '20'
         cache: 'npm'
 
     - name: Install dependencies
@@ -49,7 +49,7 @@ jobs:
     - name: Setup Node.js
       uses: actions/setup-node@v3
       with:
-        node-version: '18'
+        node-version: '20'
         cache: 'npm'
 
     - name: Install dependencies
@@ -90,7 +90,7 @@ jobs:
     - name: Setup Node.js
       uses: actions/setup-node@v3
       with:
-        node-version: '18'
+        node-version: '20'
         cache: 'npm'
 
     - name: Install dependencies