feat: chat capture (@bridge participant, onDidChangeTextDocument), !stop command, chat snapshot scanner

bot.py

@@ -114,6 +114,7 @@ class GravityBot(commands.Bot):
     async def setup_hook(self):
         self.loop.create_task(self._process_events())
         self.pending_approval_scanner.start()
+        self.chat_snapshot_scanner.start()
         logger.info("Bot setup complete")
 
     async def on_ready(self):
@@ -417,6 +418,17 @@ class GravityBot(commands.Bot):
 
         text = message.content.strip()
 
+        # Special command: !stop — cancel AI work
+        if text == "!stop":
+            self.bridge.write_command(project, "!stop", project_name=project)
+            embed = discord.Embed(
+                title="⏹️ AI 작업 중지",
+                description=f"프로젝트: **{project}**\n중지 요청을 Extension에 전달했습니다.",
+                color=discord.Color.orange(),
+            )
+            await message.channel.send(embed=embed)
+            return
+
         # Special command: !auto on/off
         if text in ("!auto on", "!auto off"):
             self.bridge.write_command(project, text, project_name=project)
@@ -439,3 +451,45 @@ class GravityBot(commands.Bot):
             await message.add_reaction("📨")
 
         await self.process_commands(message)
+
+    # ─── Chat Snapshot Scanner ─────────────────────────────────────────
+
+    @tasks.loop(seconds=5)
+    async def chat_snapshot_scanner(self):
+        """Scan bridge/chat_snapshots/ for AI response dumps."""
+        try:
+            snapshot_dir = self.bridge.bridge_dir / "chat_snapshots"
+            if not snapshot_dir.exists():
+                return
+
+            for f in snapshot_dir.glob("*.json"):
+                try:
+                    data = json.loads(f.read_text(encoding="utf-8-sig"))
+                    project = data.get("project_name", Config.PROJECT_NAME)
+                    content = data.get("content", "")
+
+                    if content:
+                        channel = await self._get_channel(project)
+                        if channel:
+                            # Split long content
+                            CHUNK = 4000
+                            chunks = [content[i:i+CHUNK] for i in range(0, len(content), CHUNK)]
+                            for i, chunk in enumerate(chunks):
+                                title = "💬 AI 대화 내용" if i == 0 else f"💬 (계속 {i+1}/{len(chunks)})"
+                                embed = discord.Embed(
+                                    title=title,
+                                    description=chunk,
+                                    color=discord.Color.purple(),
+                                    timestamp=datetime.now(timezone.utc),
+                                )
+                                await channel.send(embed=embed)
+
+                    f.unlink()  # Cleanup
+                except (json.JSONDecodeError, OSError) as e:
+                    logger.warning(f"Bad chat snapshot {f.name}: {e}")
+        except Exception as e:
+            logger.error(f"Error scanning chat snapshots: {e}")
+
+    @chat_snapshot_scanner.before_loop
+    async def before_chat_scanner(self):
+        await self.wait_until_ready()