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/__init__.py

@@ -145,7 +145,9 @@ class SentimentCog(commands.Cog):
                 mention_config = config.get("mention_scan", {})
                 if mention_config.get("enabled", True):
                     await self._maybe_start_mention_scan(message, mention_config)
-            return
+                return
+            # For non-report intents, fall through to buffer the message
+            # so it still gets scored for toxicity
 
         # Skip if empty
         if not message.content or not message.content.strip():
@@ -317,11 +319,13 @@ class SentimentCog(commands.Cog):
             if aliases:
                 anon_key = anon_map.get(msg.author.display_name, msg.author.display_name)
                 lines.append(f"  {anon_key} is also known as: {', '.join(aliases)}")
-        # Also include aliases for members NOT in the conversation (so the LLM
-        # can recognize name-drops of absent members)
+        # Include aliases for members NOT in the conversation (so the LLM
+        # can recognize name-drops of absent members), using anonymized keys
+        absent_idx = 0
         for uid, aliases in all_aliases.items():
             if uid not in seen_ids:
-                lines.append(f"  (not in chat) also known as: {', '.join(aliases)}")
+                absent_idx += 1
+                lines.append(f"  Absent_{absent_idx} is also known as: {', '.join(aliases)}")
         return "\n".join(lines) if lines else ""
 
     @staticmethod