refactor(api): TOML 配置 SSOT、统一错误契约、Auth/事务加固与可观测性 (#33)

配置 SSOT（TOML + .env）
统一错误契约
Auth 与事务边界
Redis / Celery 可靠性:业务 Redis（DB/0）与 Celery broker/backend（DB/1）显式拆分；连接池、sync client
可观测性（OpenTelemetry + LGTM）

api/app/features/memoir/memoir_images/storage.py

@@ -190,13 +190,15 @@ class TencentCosStorageService:
 
     @classmethod
     def from_settings(cls, settings) -> "TencentCosStorageService":
+        from app.core.runtime_constants import misc_defaults
+
         config = (
-            getattr(settings, "tencent_cos_secret_id", "") or "",
-            getattr(settings, "tencent_cos_secret_key", "") or "",
-            getattr(settings, "tencent_cos_region", "") or "",
-            getattr(settings, "tencent_cos_bucket", "") or "",
-            getattr(settings, "tencent_cos_base_url", "") or "",
-            getattr(settings, "tencent_cos_token", "") or "",
+            (getattr(settings, "tencent_secret_id", "") or "").strip(),
+            (getattr(settings, "tencent_secret_key", "") or "").strip(),
+            misc_defaults.tencent_cos_region,
+            (getattr(settings, "tencent_cos_bucket", "") or "").strip(),
+            (getattr(settings, "tencent_cos_base_url", "") or "").strip(),
+            "",
         )
         if cls._instance is None or cls._instance_config != config:
             cls._instance = cls(