refactor: extract sentiment cog into package with shared _process_finding

Convert cogs/sentiment.py (1050 lines) into cogs/sentiment/ package:
- __init__.py (656 lines): core SentimentCog with new _process_finding()
  that deduplicates the per-user finding loop from _process_buffered and
  _run_mention_scan (~90 lines each → single shared method)
- actions.py: mute_user, warn_user
- topic_drift.py: handle_topic_drift
- channel_redirect.py: handle_channel_redirect, build_channel_context
- coherence.py: handle_coherence_alert
- log_utils.py: log_analysis, log_action, score_color
- state.py: save_user_state, flush_dirty_states

All extracted modules use plain async functions (not methods) receiving
bot/config as parameters. Named log_utils.py to avoid shadowing stdlib
logging. Also update CLAUDE.md with comprehensive project documentation.

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

cogs/sentiment/topic_drift.py

@@ -0,0 +1,111 @@
+import asyncio
+import logging
+
+import discord
+
+from cogs.sentiment.log_utils import log_action
+from cogs.sentiment.state import save_user_state
+
+logger = logging.getLogger("bcs.sentiment")
+
+
+async def handle_topic_drift(
+    bot, message: discord.Message, topic_category: str, topic_reasoning: str,
+    db_message_id: int | None, dirty_users: set[int],
+):
+    config = bot.config.get("topic_drift", {})
+    if not config.get("enabled", True):
+        return
+
+    ignored = config.get("ignored_channels", [])
+    if message.channel.id in ignored or getattr(message.channel, "name", "") in ignored:
+        return
+
+    dry_run = bot.config.get("monitoring", {}).get("dry_run", False)
+    if dry_run:
+        return
+
+    tracker = bot.drama_tracker
+    user_id = message.author.id
+    cooldown = config.get("remind_cooldown_minutes", 10)
+
+    if not tracker.can_topic_remind(user_id, cooldown):
+        return
+
+    count = tracker.record_off_topic(user_id)
+    escalation_threshold = config.get("escalation_count", 3)
+    messages_config = bot.config.get("messages", {})
+
+    if count >= escalation_threshold and not tracker.was_owner_notified(user_id):
+        tracker.mark_owner_notified(user_id)
+        owner = message.guild.owner
+        if owner:
+            dm_text = messages_config.get(
+                "topic_owner_dm",
+                "Heads up: {username} keeps going off-topic in #{channel}. Reminded {count} times.",
+            ).format(
+                username=message.author.display_name,
+                channel=message.channel.name,
+                count=count,
+            )
+            try:
+                await owner.send(dm_text)
+            except discord.HTTPException:
+                logger.warning("Could not DM server owner about topic drift.")
+
+        await log_action(
+            message.guild,
+            f"**TOPIC DRIFT \u2014 OWNER NOTIFIED** | {message.author.mention} | "
+            f"Off-topic count: {count} | Category: {topic_category}",
+        )
+        logger.info("Notified owner about %s topic drift (count %d)", message.author, count)
+
+        asyncio.create_task(bot.db.save_action(
+            guild_id=message.guild.id, user_id=user_id,
+            username=message.author.display_name,
+            action_type="topic_escalation", message_id=db_message_id,
+            details=f"off_topic_count={count} category={topic_category}",
+        ))
+        save_user_state(bot, dirty_users, user_id)
+
+    elif count >= 2:
+        nudge_text = messages_config.get(
+            "topic_nudge",
+            "{username}, let's keep it to gaming talk in here.",
+        ).format(username=message.author.display_name)
+        await message.channel.send(nudge_text)
+        await log_action(
+            message.guild,
+            f"**TOPIC NUDGE** | {message.author.mention} | "
+            f"Off-topic count: {count} | Category: {topic_category}",
+        )
+        logger.info("Topic nudge for %s (count %d)", message.author, count)
+
+        asyncio.create_task(bot.db.save_action(
+            guild_id=message.guild.id, user_id=user_id,
+            username=message.author.display_name,
+            action_type="topic_nudge", message_id=db_message_id,
+            details=f"off_topic_count={count} category={topic_category}",
+        ))
+        save_user_state(bot, dirty_users, user_id)
+
+    else:
+        remind_text = messages_config.get(
+            "topic_remind",
+            "Hey {username}, this is a gaming server \u2014 maybe take the personal stuff to DMs?",
+        ).format(username=message.author.display_name)
+        await message.channel.send(remind_text)
+        await log_action(
+            message.guild,
+            f"**TOPIC REMIND** | {message.author.mention} | "
+            f"Category: {topic_category} | {topic_reasoning}",
+        )
+        logger.info("Topic remind for %s (count %d)", message.author, count)
+
+        asyncio.create_task(bot.db.save_action(
+            guild_id=message.guild.id, user_id=user_id,
+            username=message.author.display_name,
+            action_type="topic_remind", message_id=db_message_id,
+            details=f"off_topic_count={count} category={topic_category} reasoning={topic_reasoning}",
+        ))
+        save_user_state(bot, dirty_users, user_id)