Show agent detection state in `partio status`

[jcleira]

Summary

partio status shows the configured agent name from config (e.g. Agent: claude-code) but does not indicate whether the agent is actually detectable in the current environment. Users enabling partio for the first time have no quick way to verify that Claude Code process detection is working without making a test commit.

Proposed Change

Add a live agent detection check to partio status output:

Agent running: yes

or

Agent running: no

or

Agent running: unknown (detection error)

Inspired by entireio/cli#847 (Show installed agents in status output).

Acceptance Criteria

• partio status shows whether the configured agent (Claude Code) is currently detected as running
• When the agent process is detected running, shows Agent running: yes
• When not running, shows Agent running: no
• When detection fails with an error, shows Agent running: unknown (detection error)
• Line is only shown when partio is enabled
• Existing status output lines are preserved

Program

See .minions/programs/show-agent-detection-in-status.md for implementation details.