fix(architecture): satisfy ruff/mypy ratchets for media auxiliary

e02418bac 把新导入放在 settings = RuntimeSettingsCompat() 之后，
导致 5 个模块 E402 诊断超出只降不增基线；同时 media_auxiliary
把工厂函数 MetaInfo 误用作返回类型标注。将新增导入移回赋值语句
之前，返回类型修正为 MetaBase。

app/modules/thetvdb/__init__.py

@@ -1,15 +1,14 @@
 from threading import Lock
 from typing import Optional, Tuple, Union, cast
 
-from app.runtime.settings import RuntimeSettingsCompat
-
-settings = RuntimeSettingsCompat()
 from app.domain.context import MediaInfo
 from app.domain.media import is_media_source_enabled
 from app.domain.meta.metabase import MetaBase
+from app.runtime.execution import run_in_threadpool
+from app.runtime.settings import get_runtime_setting
+
 from app.modules import _ModuleBase
 from app.modules.thetvdb import tvdb_v4_official
-from app.runtime.execution import run_in_threadpool
 from app.runtime.log import logger
 from app.schemas.types import (
     MediaRecognizeType,
@@ -39,11 +38,11 @@ class TheTvDbModule(_ModuleBase):
         action = "刷新" if is_retry else "创建"
         logger.info(f"开始{action}TVDB登录会话...")
         try:
-            if not settings.TVDB_V4_API_KEY:
+            if not get_runtime_setting("TVDB_V4_API_KEY"):
                 raise ConnectionError("TVDB API Key 未配置，无法初始化会话。")
-            self.tvdb = tvdb_v4_official.TVDB(apikey=settings.TVDB_V4_API_KEY,
-                                              pin=settings.TVDB_V4_API_PIN,
-                                              proxy=settings.PROXY,
+            self.tvdb = tvdb_v4_official.TVDB(apikey=get_runtime_setting("TVDB_V4_API_KEY"),
+                                              pin=get_runtime_setting("TVDB_V4_API_PIN"),
+                                              proxy=get_runtime_setting("PROXY"),
                                               timeout=self.__timeout)
             if self.tvdb:
                 logger.info(f"TVDB登录会话{action}成功。")