Add two-tier LLM analysis with triage/escalation

Triage model (LLM_MODEL) handles every message cheaply. If toxicity
>= 0.25, off_topic, or coherence < 0.6, the message is re-analyzed
with the heavy model (LLM_ESCALATION_MODEL). Chat, image analysis,
/bcs-test, and /bcs-scan always use the heavy model.

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

cogs/sentiment.py

@@ -141,7 +141,7 @@ class SentimentCog(commands.Cog):
         game_channels = config.get("game_channels", {})
         channel_context = self._build_channel_context(message, game_channels)
 
-        # Analyze the combined message
+        # Analyze the combined message (triage with lightweight model)
         context = self._get_context(message)
         user_notes = self.bot.drama_tracker.get_user_notes(message.author.id)
         result = await self.bot.llm.analyze_message(
@@ -152,6 +152,26 @@ class SentimentCog(commands.Cog):
         if result is None:
             return
 
+        # Escalation: re-analyze with heavy model if triage flags something
+        escalation_threshold = sentiment_config.get("escalation_threshold", 0.25)
+        needs_escalation = (
+            result["toxicity_score"] >= escalation_threshold
+            or result.get("off_topic", False)
+            or result.get("coherence_score", 1.0) < 0.6
+        )
+        if needs_escalation:
+            triage_score = result["toxicity_score"]
+            heavy_result = await self.bot.llm_heavy.analyze_message(
+                combined_content, context, user_notes=user_notes,
+                channel_context=channel_context,
+            )
+            if heavy_result is not None:
+                logger.info(
+                    "Escalated to heavy model (triage_score=%.2f) for %s",
+                    triage_score, message.author.display_name,
+                )
+                result = heavy_result
+
         score = result["toxicity_score"]
         categories = result["categories"]
         reasoning = result["reasoning"]