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>

angular.json

@@ -460,6 +460,36 @@
           }
         }
       }
+    },
+    "auth-client": {
+      "projectType": "library",
+      "root": "projects/auth-client",
+      "sourceRoot": "projects/auth-client/src",
+      "prefix": "lib",
+      "architect": {
+        "build": {
+          "builder": "@angular/build:ng-packagr",
+          "configurations": {
+            "production": {
+              "tsConfig": "projects/auth-client/tsconfig.lib.prod.json"
+            },
+            "development": {
+              "tsConfig": "projects/auth-client/tsconfig.lib.json"
+            }
+          },
+          "defaultConfiguration": "production"
+        },
+        "test": {
+          "builder": "@angular/build:karma",
+          "options": {
+            "tsConfig": "projects/auth-client/tsconfig.spec.json",
+            "polyfills": [
+              "zone.js",
+              "zone.js/testing"
+            ]
+          }
+        }
+      }
     }
   }
 }