Add auth-client library for Elixir auth service integration

- Complete Angular client library for authentication and authorization
- JWT token management with automatic refresh and storage
- OAuth integration with social providers (Google, GitHub, etc.)
- Two-factor authentication support (TOTP and backup codes)
- Route guards for authentication and scope-based authorization
- HTTP interceptor for automatic token injection and refresh
- Comprehensive TypeScript interfaces for all API models
- User management features (profile updates, password changes)
- Cross-tab synchronization and token validation
- Complete usage guide with practical examples

🤖 Generated with [Claude Code](https://claude.ai/code)

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

package.json

@@ -29,6 +29,7 @@
   },
   "devDependencies": {
     "@angular-devkit/build-angular": "^19.2.15",
+    "@angular/build": "^20.2.0",
     "@angular/cli": "^19.2.15",
     "@angular/compiler-cli": "^19.2.0",
     "@types/jasmine": "~5.1.0",
@@ -42,4 +43,4 @@
     "ng-packagr": "^19.2.0",
     "typescript": "~5.7.2"
   }
-}
+}