fix(bridge): 채널 중복 생성 race condition 수정 + AG- 접두사 + metadata 모니터링

config.py

@@ -34,12 +34,17 @@ class Config:
         "walkthrough.md",
     }
 
+    # Also monitor these patterns (matched by suffix)
+    WATCHED_SUFFIXES: set = {
+        ".metadata.json",  # artifact summary changes
+    }
+
     # Discord message limits
     DISCORD_MSG_LIMIT: int = 2000
     DISCORD_EMBED_DESC_LIMIT: int = 4096
 
     # Channel naming
-    CHANNEL_PREFIX: str = "gravity"
+    CHANNEL_PREFIX: str = "AG"
 
     @classmethod
     def validate(cls) -> list[str]: