style: 统一使用 PEP 604/585 现代类型语法

- Optional[X] → X | None
- Dict[X, Y] → dict[X, Y]
- List[X] → list[X]
- Tuple[X, Y] → tuple[X, Y]
- Set[X] → set[X]

涉及 10 个文件，共约 50 处改动。

src/services/billing/calculator.py

@@ -295,7 +295,7 @@ def calculate_request_cost(
             "cache_cost": float,
             "request_cost": float,
             "total_cost": float,
-            "tier_index": Optional[int],
+            "tier_index": int | None,
         }
     """
     # 构建标准化 usage

src/services/gemini_files_mapping.py

@@ -34,7 +34,7 @@ async def store_file_key_mapping(file_name: str, key_id: str) -> None:
     await CacheService.set(cache_key, str(key_id), ttl_seconds=FILE_MAPPING_TTL_SECONDS)
 
 
-async def get_file_key_mapping(file_name: str) -> Optional[str]:
+async def get_file_key_mapping(file_name: str) -> str | None:
     cache_key = build_file_mapping_key(file_name)
     if not cache_key:
         return None
@@ -50,7 +50,7 @@ async def delete_file_key_mapping(file_name: str) -> None:
         await CacheService.delete(cache_key)
 
 
-def _extract_file_name_from_uri(file_uri: str) -> Optional[str]:
+def _extract_file_name_from_uri(file_uri: str) -> str | None:
     """
     从 fileUri 提取 files/xxx 名称。
 
@@ -70,11 +70,11 @@ def _extract_file_name_from_uri(file_uri: str) -> Optional[str]:
     return None
 
 
-def extract_file_names_from_request(payload: Optional[Dict[str, Any]]) -> Set[str]:
+def extract_file_names_from_request(payload: dict[str, Any] | None) -> set[str]:
     """
     从 Gemini 请求体中提取 fileUri 使用到的 files/xxx 名称集合。
     """
-    results: Set[str] = set()
+    results: set[str] = set()
 
     def walk(node: Any) -> None:
         if isinstance(node, dict):

src/services/provider/transport.py

@@ -72,8 +72,8 @@ def build_provider_url(
     query_params: dict[str, Any] | None = None,
     path_params: dict[str, Any] | None = None,
     is_stream: bool = False,
-    key: Optional["ProviderAPIKey"] = None,
-    decrypted_auth_config: Optional[Dict[str, Any]] = None,
+    key: "ProviderAPIKey" | None = None,
+    decrypted_auth_config: dict[str, Any] | None = None,
 ) -> str:
     """
     根据 endpoint 配置生成请求 URL
@@ -175,7 +175,7 @@ def _resolve_default_path(api_format: str | None) -> str:
 
 # Vertex AI 模型默认 region 映射
 # 用户可以通过 auth_config.model_regions 覆盖
-VERTEX_AI_DEFAULT_MODEL_REGIONS: Dict[str, str] = {
+VERTEX_AI_DEFAULT_MODEL_REGIONS: dict[str, str] = {
     # Gemini 3 系列（使用 global）
     "gemini-3-pro-image-preview": "global",
     # Gemini 2.0 系列
@@ -200,10 +200,10 @@ VERTEX_AI_DEFAULT_MODEL_REGIONS: Dict[str, str] = {
 def _build_vertex_ai_url(
     key: "ProviderAPIKey",
     *,
-    path_params: Optional[Dict[str, Any]] = None,
-    query_params: Optional[Dict[str, Any]] = None,
+    path_params: dict[str, Any] | None = None,
+    query_params: dict[str, Any] | None = None,
     is_stream: bool = False,
-    decrypted_auth_config: Optional[Dict[str, Any]] = None,
+    decrypted_auth_config: dict[str, Any] | None = None,
 ) -> str:
     """
     构建 Vertex AI URL
@@ -236,7 +236,7 @@ def _build_vertex_ai_url(
     from src.core.crypto import crypto_service
 
     # 优先使用传入的已解密配置，避免重复解密
-    auth_config: Dict[str, Any] = {}
+    auth_config: dict[str, Any] = {}
     if decrypted_auth_config:
         auth_config = decrypted_auth_config
     else: