feat: add unblock-nag detection and redirect

Keyword-based detection for users repeatedly asking to be unblocked in
chat. Fires an LLM-generated snarky redirect (with static fallback),
tracks per-user nag count with escalating sass, and respects a 30-min
cooldown. Configurable via config.yaml unblock_nag section.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cogs/sentiment/__init__.py

@@ -13,6 +13,7 @@ from cogs.sentiment.coherence import handle_coherence_alert
 from cogs.sentiment.log_utils import log_analysis
 from cogs.sentiment.state import flush_dirty_states
 from cogs.sentiment.topic_drift import handle_topic_drift
+from cogs.sentiment.unblock_nag import handle_unblock_nag, matches_unblock_nag
 
 logger = logging.getLogger("bcs.sentiment")
 
@@ -153,6 +154,12 @@ class SentimentCog(commands.Cog):
         if not message.content or not message.content.strip():
             return
 
+        # Check for unblock nagging (keyword-based, no LLM needed for detection)
+        if matches_unblock_nag(message.content):
+            asyncio.create_task(handle_unblock_nag(
+                self.bot, message, self._dirty_users,
+            ))
+
         # Buffer the message and start/reset debounce timer (per-channel)
         channel_id = message.channel.id
         if channel_id not in self._message_buffer: