fix: clear ruff F811/F841 findings across frontends and helpers

[Kailigithub]

fix: clear ruff F811/F841 findings across frontends and helpers

Resolve all F811 (redefined-while-unused) and F841 (unused-local) issues
reported by ruff so the lint baseline is cleaner:

• frontends/tui_v3.py: drop a duplicate from dataclasses import dataclass line that was shadowed by the very next import; remove the
  dead from prompt_toolkit.keys import Keys block in
  _ptk_keypress_to_bytes — the symbol was never referenced in the
  function body, only getattr(kp, 'key', None) is used.
• frontends/fsapp.py: handle_message unpacks data.event but never reads
  the event object — rename to _event to flag intent.
• frontends/genericagent_acp_bridge.py: write_message computed method
  but only logged the payload — embed method in the ACP-BRIDGE log line
  so the local is used and debugging is easier.
• frontends/qtapp.py: drop unused as e from an exception handler that
  already prints via traceback.print_exc().
• frontends/tuiapp.py: drop the unused args assignment in main();
  parse_args still validates argv and surfaces errors.
• memory/autonomous_operation_sop/helper.py: remove an unused errors
  list in complete_task.

Verification:

• python3 -m py_compile on all six files passes.
• ruff check <files> --select F811,F841 reports All checks passed!.
• No behavioural change; the only logic tweak is the ACP-BRIDGE log
  gaining a [method] prefix.