feat: upgrade NestJS to v11 and migrate to ESLint flat config (#10746)

### Description

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  ✍️ Write a short summary of your work.
  If necessary, include relevant screenshots.
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This PR upgrades the NestJS example from v10 to v11 and modernizes the
project configuration. The main changes include:

- **NestJS Upgrade**: Upgrade `@nestjs/common`, `@nestjs/core`, and
`@nestjs/platform-express` from v10 to v11
- **ESLint Migration**: Migrate from legacy `.eslintrc.js` format to
modern flat config format using `eslint.config.mjs`
- **Configuration Cleanup**: Remove legacy configuration files
(`.eslintrc.js`, `.prettierrc.js`) and replace with modern equivalents
- **Package Updates**: Update dependencies and scripts across all
packages in the monorepo
- **Project Structure**: Modernize the overall project structure with
updated TypeScript and build configurations

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  Give a quick description of steps to test your changes.
-->

## Testing Instructions

1. **Install Dependencies**
   ```bash
   pnpm install
   pnpm build
   ```

2. **Verify NestJS API**
   ```bash
   pnpm --filter=api run dev
   ```
   - Check that the API starts without errors
   - Verify endpoints are accessible at `http://localhost:3000`

3. **Test Web Application**
   ```bash
   pnpm --filter=web run dev
   ```
   - Ensure the web app runs on `http://localhost:3001`
   - Verify the UI displays correctly

4. **Linting and Formatting**
   ```bash
   pnpm run lint
   pnpm run format
   ```
   - Confirm ESLint runs without errors
   - Verify Prettier formatting works correctly

5. **Build Process**
   ```bash
   pnpm build
   ```
   - Ensure all packages build successfully
   - Check for any TypeScript compilation errors

6. **Run Tests**
   ```bash
   pnpm test
   ```
   - Verify all tests pass
   - Check that Jest configuration works properly

Author: iamnivekx

examples/with-nestjs/.eslintrc.js

@@ -0,0 +1,23 @@
+import { libraryConfig } from "@repo/eslint-config/library";
+import tsParser from "@typescript-eslint/parser";
+
+export default [
+  {
+    ignores: ["apps/**", "packages/**", "dist/**", "node_modules/**"],
+  },
+  ...libraryConfig,
+  {
+    parser: tsParser,
+    parserOptions: {
+      project: true,
+    },
+  },
+  {
+    rules: {
+      // add override for any (a metric ton of them, initial conversion)
+      "@typescript-eslint/no-explicit-any": "off",
+      // we generally use this in isFunction, not via calling
+      "@typescript-eslint/unbound-method": "off",
+    },
+  },
+];

examples/with-nestjs/.eslintrc.mjs

@@ -0,0 +1,4 @@
+import config from "@repo/eslint-config/prettier-base";
+
+/** @type {import("prettier").Config} */
+export default config;

examples/with-nestjs/.prettierrc.js

@@ -0,0 +1,4 @@
+import config from "@repo/eslint-config/prettier-base";
+
+/** @type {import("prettier").Config} */
+export default config;

examples/with-nestjs/.prettierrc.mjs

@@ -0,0 +1,4 @@
+import { nestJsConfig } from "@repo/eslint-config/nest-js";
+
+/** @type {import("eslint").Linter.Config} */
+export default nestJsConfig;

examples/with-nestjs/apps/api/.eslintrc.js

@@ -1,3 +1,3 @@
-import { config } from '@repo/jest-config/nest';
+import { nestConfig } from '@repo/jest-config';
 
-export default config;
+export default nestConfig;

examples/with-nestjs/apps/api/.prettierrc.js

@@ -15,27 +15,27 @@
     "lint": "eslint \"{src,apps,libs,test}/**/*.ts\""
   },
   "dependencies": {
-    "@nestjs/common": "^10.0.0",
-    "@nestjs/core": "^10.0.0",
-    "@nestjs/platform-express": "^10.0.0",
+    "@nestjs/common": "^11.0.0",
+    "@nestjs/core": "^11.0.0",
+    "@nestjs/platform-express": "^11.0.0",
     "@repo/api": "workspace:*",
     "reflect-metadata": "^0.2.0",
     "rxjs": "^7.8.1"
   },
   "devDependencies": {
     "@jest/globals": "^29.7.0",
-    "@nestjs/cli": "^10.0.0",
-    "@nestjs/schematics": "^10.0.0",
-    "@nestjs/testing": "^10.0.0",
+    "@nestjs/cli": "^11.0.0",
+    "@nestjs/schematics": "^11.0.0",
+    "@nestjs/testing": "^11.0.0",
     "@repo/eslint-config": "workspace:*",
     "@repo/jest-config": "workspace:*",
     "@repo/typescript-config": "workspace:*",
     "@types/express": "^4.17.17",
-    "@types/node": "^20.3.1",
+    "@types/node": "^22.10.7",
     "@types/supertest": "^6.0.0",
     "jest": "^29.7.0",
     "source-map-support": "^0.5.21",
-    "supertest": "^6.3.3",
+    "supertest": "^7.0.0",
     "ts-jest": "^29.2.5",
     "ts-loader": "^9.4.3",
     "ts-node": "^10.9.2",