Feature request: statusline refreshInterval setting for periodic updates

Feature Request

Add a refreshInterval option to the statusline configuration so the status line script can be re-executed on a timer, not just on events.

Current Behavior

The statusline command script only runs on specific events (assistant messages, permission changes, vim mode toggles), debounced at 300ms. There is no way to trigger periodic re-execution.

Desired Behavior

A new refreshInterval field in the statusline settings:

{
  "statusLine": {
    "type": "command",
    "command": "/path/to/statusline-command.sh",
    "refreshInterval": 1000
  }
}

This would re-run the script every refreshInterval milliseconds in addition to the existing event-driven updates.

Use Case

I have a retro LED clock in my status line that displays HH:MM:SS. The seconds are stale between interactions since the script only runs on events. A 1-second refresh interval would make it a live clock.

More broadly, any status line element that tracks real-time state (elapsed time, system load, background process status, memory usage) would benefit from periodic refresh.

Suggested Defaults

• refreshInterval: optional, no default (preserves current behavior)
• Minimum: 500ms (to avoid perf issues)
• The interval timer should reset on event-driven updates to avoid redundant executions

Environment

• Claude Code on macOS (Ghostty terminal)
• Using a bash script statusline command