fix(logging): replace structlog with stdlib logging to prevent broken pipe crashes

structlog fails with BrokenPipeError when stdout is redirected (e.g., background
processes, Docker logs). Replace all structlog.get_logger() calls with
logging.getLogger() and convert keyword-style log calls to %-format strings.

Also removes stale Docs/tasks.md (2028 lines) and updates Robot Framework
tests to match current API behavior.

src/server/services/image_loading_service.py

@@ -91,14 +91,13 @@ class ImageLoadingService:
         # Get series from database to retrieve TMDB ID
         series = await AnimeSeriesService.get_by_key(db, key)
         if not series:
-            logger.warning("Series not found in database", key=key)
+            logger.warning("Series not found in database key=%s", key)
             return {"poster": False, "fanart": False, "logo": False}
 
         if not series.tmdb_id:
             logger.warning(
-                "Series has no TMDB ID, cannot load images",
-                key=key,
-                name=series.name,
+                "Series has no TMDB ID, cannot load images key=%s name=%s",
+                key, series.name,
             )
             return {"poster": False, "fanart": False, "logo": False}