feat(storage): add delete_href method to remove files and clean up empty directories

chore(docker): remove MongoDB service and related configurations from local setup

feat(migrations): create ChapterMeta table and add search_name, size_bytes, mtime_epoch, lastScannedAt, review_status, and review_payload columns to SourceAsset

chore(dependencies): remove motor and pymongo from project dependencies

app/config.py

@@ -8,7 +8,6 @@ class Settings(BaseSettings):
     app_env: str = "development"
 
     database_url: str
-    mongodb_uri: str = ""
 
     google_client_id: str = ""
     nextauth_secret: str = ""
@@ -22,13 +21,15 @@ class Settings(BaseSettings):
     r2_public_base_url: str = ""
     nas_content_root: str = "./data/content"
     epub_source_root: str = "./data/epub-source"
-    chapter_content_mode: str = "nas_first"  # nas_first | mongo_first
+    chapter_content_mode: str = "nas_first"
     auto_schema_bootstrap: str = "false"
 
     deepseek_key: str = ""
     deepseek_model: str = "deepseek-chat"
     openrouter_key: str = ""
     openrouter_paused: str = "true"
+    import_scan_interval_minutes: int = 30
+    import_scan_limit: int = 2000
 
     @property
     def google_client_id_list(self) -> list[str]: