feat(gateway): Docker Gateway 봇 + HTTP API 구현 #task-311

- gateway.py: Collector↔Gateway HTTP API (pending, response, chat, register, commands)
- Dockerfile + docker-compose.yml: BOT_MODE=gateway, port 8585
- main.py: gateway 모드 (watcher 비활성, GatewayAPI 시작)
- config.py: gateway 모드 BRAIN_PATH 검증 스킵
- requirements.txt: aiohttp 추가
- docs/usage-guide.md: Docker 배포 섹션 추가
- Extension VSIX v0.3.9 빌드 (auto-approve 포함)

main.py

@@ -6,6 +6,7 @@ Entry point that runs the brain watcher and Discord bot together.
 import asyncio
 import io
 import logging
+import os
 import sys
 
 from config import Config
@@ -61,7 +62,9 @@ async def main():
         logger.info(f"Remote transport: {Config.REMOTE_BRIDGE_URL}")
 
     # Create components
-    watcher = BrainWatcher(event_queue, loop)
+    watcher = None
+    if Config.BOT_MODE != 'gateway':
+        watcher = BrainWatcher(event_queue, loop)
     bot = GravityBot(event_queue)
 
     # Inject transport if specified (otherwise bot uses default LocalTransport)
@@ -70,9 +73,20 @@ async def main():
         bot.bridge = BridgeProtocol(transport)
 
     try:
-        # Start watcher (runs in a separate thread via watchdog)
-        watcher.start()
-        logger.info(f"Watcher started, {len(watcher.known_sessions)} existing sessions")
+        # Start watcher (local mode only — gateway receives data via HTTP)
+        if watcher:
+            watcher.start()
+            logger.info(f"Watcher started, {len(watcher.known_sessions)} existing sessions")
+        else:
+            logger.info("Gateway mode — watcher disabled (data via HTTP API)")
+
+        # Start Gateway HTTP API (gateway mode)
+        if Config.BOT_MODE == 'gateway':
+            from gateway import GatewayAPI
+            gateway_port = int(os.environ.get('GATEWAY_PORT', '8585'))
+            gateway = GatewayAPI(bot, port=gateway_port)
+            await gateway.start()
+            logger.info(f"Gateway API running on port {gateway_port}")
 
         # Run Discord bot (blocks until bot disconnects)
         await bot.start(Config.DISCORD_TOKEN)
@@ -83,7 +97,8 @@ async def main():
         logger.error(f"Fatal error: {e}", exc_info=True)
     finally:
         # Cleanup
-        watcher.stop()
+        if watcher:
+            watcher.stop()
         if not bot.is_closed():
             await bot.close()
         logger.info("Gravity Control shutdown complete")