refactor(cleanup): v0.5.0 Collector 제거 + dead code 정리 + HttpBridgeContext 버그 수정

- DELETE collector.py (523줄)
- main.py: BOT_MODE=remote 분기 제거
- gateway.py: Collector REST 6개 endpoint 제거 (311→168줄)
- bridge.py: RemoteTransport 제거 (480→270줄)
- config.py: REMOTE_BRIDGE_URL 제거
- extension.ts: dead code 4개 + stale module vars 제거
- step-probe.ts: getStepProbeContext() 추가, autoApproveEnabled 제거
- FIX: HttpBridgeContext stale primitive (getter 패턴으로 수정)
- ADD: extension.log rotation (10MB→2MB tail)
- docs: architecture.md, tech-stack.md, known-issues.md 업데이트

main.py

@@ -51,47 +51,6 @@ async def main():
     # Get the running loop
     loop = asyncio.get_running_loop()
 
-    # ── Collector mode (DEPRECATED): no Discord bot, just relay local ↔ Gateway ──
-    if Config.BOT_MODE == "remote":
-        logger.warning("=" * 50)
-        logger.warning("⚠️  Collector mode (BOT_MODE=remote) is DEPRECATED")
-        logger.warning("Extension이 WebSocket으로 Hub에 직접 연결합니다.")
-        logger.warning("BOT_MODE=gateway로 전환하세요.")
-        logger.warning("=" * 50)
-
-        from bridge import LocalTransport, RemoteTransport
-        from collector import CollectorBridge
-
-        if not Config.REMOTE_BRIDGE_URL:
-            logger.error("REMOTE_BRIDGE_URL is required for remote (Collector) mode")
-            sys.exit(1)
-
-        bridge_dir = Config.BRAIN_PATH.parent / "bridge"
-        local = LocalTransport(bridge_dir)
-        local.ensure_dirs()
-        remote = RemoteTransport(Config.REMOTE_BRIDGE_URL, api_key=Config.GATEWAY_API_KEY)
-
-        collector = CollectorBridge(local, remote, project_name=Config.PROJECT_NAME,
-                                    event_queue=event_queue)
-        logger.info(f"Collector mode: {Config.REMOTE_BRIDGE_URL}")
-
-        # Optionally start watcher for brain events (local display only)
-        watcher = BrainWatcher(event_queue, loop)
-
-        try:
-            watcher.start()
-            logger.info(f"Watcher started, {len(watcher.known_sessions)} existing sessions")
-            await collector.start()
-        except KeyboardInterrupt:
-            logger.info("Received keyboard interrupt")
-        except Exception as e:
-            logger.error(f"Fatal error: {e}", exc_info=True)
-        finally:
-            await collector.stop()
-            watcher.stop()
-            logger.info("Collector shutdown complete")
-        return
-
     # ── Local / Gateway mode ──
 
     # Create components