Upload patch_agent_backend.py

Fix silent auto-approve failure: anchor correctly, add runtime opt-out, drop dead mid-task block

Fix ordering bug in v2: anchor after auto-approval attrs are initialized so set_auto_approval_policy is not overwritten

Fix auto-approve: wrong anchor (multi-line __init__ signature) AND wrong API (auto_approval dict vs auto_approval_enabled flag)

patches: agent_loop detection + auto-approve toggle