fix: address multiple bugs found in code review

- Fix dirty-user flush race: discard IDs individually after successful save
- Escape LIKE wildcards in LLM-generated topic keywords for DB queries
- Anonymize absent-member aliases to prevent LLM de-anonymization
- Pass correct MIME type to vision model based on image file extension
- Use enumerate instead of list.index() in bcs-scan loop
- Allow bot @mentions with non-report intent to fall through to moderation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cogs/sentiment/state.py

@@ -32,19 +32,24 @@ async def flush_dirty_states(bot, dirty_users: set[int]) -> None:
     if not dirty_users:
         return
     dirty = list(dirty_users)
-    dirty_users.clear()
+    saved = 0
     for user_id in dirty:
         user_data = bot.drama_tracker.get_user(user_id)
-        await bot.db.save_user_state(
-            user_id=user_id,
-            offense_count=user_data.offense_count,
-            immune=user_data.immune,
-            off_topic_count=user_data.off_topic_count,
-            baseline_coherence=user_data.baseline_coherence,
-            user_notes=user_data.notes or None,
-            warned=user_data.warned_since_reset,
-            last_offense_at=user_data.last_offense_time or None,
-            aliases=_aliases_csv(user_data),
-            warning_expires_at=user_data.warning_expires_at or None,
-        )
-    logger.info("Flushed %d dirty user states to DB.", len(dirty))
+        try:
+            await bot.db.save_user_state(
+                user_id=user_id,
+                offense_count=user_data.offense_count,
+                immune=user_data.immune,
+                off_topic_count=user_data.off_topic_count,
+                baseline_coherence=user_data.baseline_coherence,
+                user_notes=user_data.notes or None,
+                warned=user_data.warned_since_reset,
+                last_offense_at=user_data.last_offense_time or None,
+                aliases=_aliases_csv(user_data),
+                warning_expires_at=user_data.warning_expires_at or None,
+            )
+            dirty_users.discard(user_id)
+            saved += 1
+        except Exception:
+            logger.exception("Failed to flush state for user %d", user_id)
+    logger.info("Flushed %d/%d dirty user states to DB.", saved, len(dirty))