feat(backend): 添加核心架构模块

- 添加认证模块 (auth.py)
- 添加 CRUD 基础操作 (crud.py)
- 添加异常处理 (exceptions.py)
- 添加日志模块 (logging.py)
- 添加响应格式 (response.py)
- 添加依赖注入 (dependencies.py)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/core/auth.py

@@ -0,0 +1,38 @@
+"""
+API Key Authentication
+API Key 认证中间件
+"""
+from typing import Optional
+from fastapi import Header, HTTPException, Request
+from fastapi.security import APIKeyHeader
+
+from app.core.config import get_settings
+
+settings = get_settings()
+
+# API Key header
+API_KEY_HEADER = APIKeyHeader(name="X-API-Key", auto_error=False)
+
+
+async def verify_api_key(api_key: Optional[str] = Header(None)) -> str:
+    """Verify API key from header"""
+    if not api_key:
+        raise HTTPException(status_code=401, detail="API key is required")
+
+    # In production, you would validate against a database or cache
+    # For development, we can use a simple validation
+    if settings.DEBUG and api_key == "dev-api-key":
+        return api_key
+
+    # TODO: Implement proper API key validation
+    # This is a placeholder - in production, validate against stored keys
+    if len(api_key) < 32:
+        raise HTTPException(status_code=401, detail="Invalid API key")
+
+    return api_key
+
+
+def create_api_key() -> str:
+    """Generate a new API key"""
+    import secrets
+    return secrets.token_hex(32)