Feature request: statusLine refreshInterval for periodic updates

Problem

The statusLine script only updates on specific events (assistant message complete, permission mode change, vim toggle). During long tool executions, thinking, or while typing, the context usage bar goes stale.

For power users tracking context consumption across long sessions with many agents, the bar is most useful exactly when it doesn't update — during heavy processing.

Proposed solution

Add an optional refreshInterval property to the statusLine config:

{
  "statusLine": {
    "type": "command",
    "command": "bash ~/.claude/statusline.sh",
    "refreshInterval": 5000
  }
}

This would re-invoke the script every N milliseconds with the latest available metadata, even between event triggers.

Alternatives considered

• /context command works but breaks flow
• Hooks (PostToolUse) fire but don't refresh the statusline
• Background polling from the script isn't possible since context data only comes from Claude Code's internal state