Backport status fast-path and CLI plain-text render handling

[bitifirefly]

Summary

• fast-path /status handling in the agent run loop so status replies can be returned immediately without entering normal message processing
• add explicit metadata={"render_as": "text"} for /status and /help command responses
• update CLI rendering to honor response metadata and keep command-style output in plain text even when markdown mode is enabled
• add regression coverage for status fast-path interception and CLI render selection

Testing

• ruff check opencane/agent/loop.py opencane/cli/commands.py tests/test_agent_loop_status_command.py tests/test_cli_input.py
• pytest -q tests/test_agent_loop_status_command.py tests/test_cli_input.py tests/test_cron_run_command.py
• pytest -q (434 passed)