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

config.py

@@ -43,9 +43,8 @@ class Config:
     CHANNEL_PREFIX: str = "AG"
     PROJECT_NAME: str = os.getenv("PROJECT_NAME", "gravity_control")
 
-    # Bot mode: 'local' (file-based bridge) or 'remote' (HTTP polling — future)
+    # Bot mode: 'local' (file-based bridge) or 'gateway' (WS Hub + HTTP API)
     BOT_MODE: str = os.getenv("BOT_MODE", "local")
-    REMOTE_BRIDGE_URL: str = os.getenv("REMOTE_BRIDGE_URL", "")
     GATEWAY_API_KEY: str = os.getenv("GATEWAY_API_KEY", "")
 
     # WebSocket Hub