feat(bot,bridge): P1 !auto 토글 자동승인 + P2 BridgeTransport 추상화 #task-304 #task-305

P1: !auto 토글 (bot.py + extension.ts)
- auto_approve_projects set으로 프로젝트별 상태 관리
- !auto → on/off 토글, pending 자동 승인 + 🤖 자동 승인됨 embed
- Extension step_probe에서 autoApproveEnabled 시 직접 tryApprovalStrategies

P2: BridgeTransport 추상화 (bridge.py)
- BridgeTransport ABC + LocalTransport (기존 동작 100% 호환)
- RemoteTransport 스켈레톤 (multi-PC 대비)
- config.py BOT_MODE/REMOTE_BRIDGE_URL, main.py transport 주입

docs: usage-guide.md + tech-stack.md Python 경로 기록

main.py

@@ -42,6 +42,7 @@ async def main():
     logger.info("=" * 50)
     logger.info(f"Brain path: {Config.BRAIN_PATH}")
     logger.info(f"Debounce: {Config.DEBOUNCE_SECONDS}s")
+    logger.info(f"Bot mode: {Config.BOT_MODE}")
 
     # Shared event queue
     event_queue = asyncio.Queue()
@@ -49,10 +50,25 @@ async def main():
     # Get the running loop
     loop = asyncio.get_running_loop()
 
+    # Create transport based on BOT_MODE
+    transport = None  # None → LocalTransport (default)
+    if Config.BOT_MODE == "remote":
+        from bridge import RemoteTransport
+        if not Config.REMOTE_BRIDGE_URL:
+            logger.error("REMOTE_BRIDGE_URL is required for remote mode")
+            sys.exit(1)
+        transport = RemoteTransport(Config.REMOTE_BRIDGE_URL)
+        logger.info(f"Remote transport: {Config.REMOTE_BRIDGE_URL}")
+
     # Create components
     watcher = BrainWatcher(event_queue, loop)
     bot = GravityBot(event_queue)
 
+    # Inject transport if specified (otherwise bot uses default LocalTransport)
+    if transport is not None:
+        from bridge import BridgeProtocol
+        bot.bridge = BridgeProtocol(transport)
+
     try:
         # Start watcher (runs in a separate thread via watchdog)
         watcher.start()