feat: Initial commit - Task Reporter incident response system

Complete implementation of the production line incident response system (生產線異常即時反應系統) including:

Backend (FastAPI):
- User authentication with AD integration and session management
- Chat room management (create, list, update, members, roles)
- Real-time messaging via WebSocket (typing indicators, reactions)
- File storage with MinIO (upload, download, image preview)

Frontend (React + Vite):
- Authentication flow with token management
- Room list with filtering, search, and pagination
- Real-time chat interface with WebSocket
- File upload with drag-and-drop and image preview
- Member management and room settings
- Breadcrumb navigation
- 53 unit tests (Vitest)

Specifications:
- authentication: AD auth, sessions, JWT tokens
- chat-room: rooms, members, templates
- realtime-messaging: WebSocket, messages, reactions
- file-storage: MinIO integration, file management
- frontend-core: React SPA structure

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

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

app/core/config.py

@@ -0,0 +1,43 @@
+"""Application configuration loaded from environment variables"""
+from pydantic_settings import BaseSettings
+from functools import lru_cache
+
+
+class Settings(BaseSettings):
+    """Application settings"""
+
+    # Database
+    DATABASE_URL: str
+
+    # Security
+    FERNET_KEY: str
+
+    # AD API
+    AD_API_URL: str
+
+    # Session Settings
+    SESSION_INACTIVITY_DAYS: int = 3
+    TOKEN_REFRESH_THRESHOLD_MINUTES: int = 5
+    MAX_REFRESH_ATTEMPTS: int = 3
+
+    # Server
+    HOST: str = "0.0.0.0"
+    PORT: int = 8000
+    DEBUG: bool = True
+
+    # MinIO Object Storage
+    MINIO_ENDPOINT: str = "localhost:9000"
+    MINIO_ACCESS_KEY: str = "minioadmin"
+    MINIO_SECRET_KEY: str = "minioadmin"
+    MINIO_BUCKET: str = "task-reporter-files"
+    MINIO_SECURE: bool = False  # Use HTTPS
+
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+
+@lru_cache()
+def get_settings() -> Settings:
+    """Get cached settings instance"""
+    return Settings()