Debug logging on LB rolling-mirror bulk ensure

Temporary instrumentation — bulk ensure path silently created
only one rolling mirror despite multiple known series members
existing in the LB cache. Promotes the bulk-ensure summary +
per-title match notes to INFO level so the next refresh
surfaces in the server log:

- ``[LB Rolling] Bulk ensure walking N cached titles for profile X``
- ``[LB Rolling] Title matched series: <title> -> <series_id>``
- ``[LB Rolling] Bulk ensure done — M/N titles matched a series``

Plus the outer ``except`` is bumped from debug to warning so a
genuine SELECT failure stops being invisible.

Once the root cause is identified the noise can drop back to
debug.

core/listenbrainz_manager.py

@@ -245,10 +245,24 @@ class ListenBrainzManager:
                 (self.profile_id,),
             )
             titles = [row[0] for row in cursor.fetchall() if row[0]]
+            logger.info(
+                f"[LB Rolling] Bulk ensure walking {len(titles)} cached titles for profile {self.profile_id}"
+            )
+            from core.playlists.lb_series import detect_series
+            matched = 0
             for title in titles:
+                m = detect_series(title)
+                if m is not None:
+                    matched += 1
+                    logger.info(
+                        f"[LB Rolling] Title matched series: {title!r} -> {m.series_id}"
+                    )
                 self._ensure_rolling_series_mirror(cursor, title)
+            logger.info(
+                f"[LB Rolling] Bulk ensure done — {matched}/{len(titles)} titles matched a series"
+            )
         except Exception as exc:
-            logger.debug(f"Bulk rolling-mirror ensure skipped: {exc}")
+            logger.warning(f"Bulk rolling-mirror ensure skipped: {exc}")
 
     def _ensure_rolling_series_mirror(self, cursor, playlist_title: str):
         """Upsert a placeholder ``mirrored_playlists`` row for the