fix: surface configured sandbox mounts to agents (#1638)

* fix: surface configured sandbox mounts to agents

* fix: address PR review feedback

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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/packages/harness/deerflow/subagents/builtins/bash_agent.py

@@ -37,6 +37,7 @@ You have access to the sandbox environment:
 - User uploads: `/mnt/user-data/uploads`
 - User workspace: `/mnt/user-data/workspace`
 - Output files: `/mnt/user-data/outputs`
+- Deployment-configured custom mounts may also be available at other absolute container paths; use them directly when the task references those mounted directories
 </working_directory>
 """,
     tools=["bash", "ls", "read_file", "write_file", "str_replace"],  # Sandbox tools only