refactor: set default config path in RockAgent.install method (#346)

Author: BCeZn

rock/sdk/sandbox/agent/rock_agent.py

@@ -186,7 +186,7 @@ def __init__(self, sandbox: Sandbox):
         self.config: RockAgentConfig | None = None
         self.agent_session: str | None = None
 
-    async def install(self, config: str | RockAgentConfig) -> None:
+    async def install(self, config: str | RockAgentConfig = "rock_agent_config.yaml") -> None:
         """Install and initialize RockAgent.
 
         Args: