feat: add confirmation dialogs before destructive actions in navigator

[gr3enarr0w]

Summary

Pressing x in the navigator immediately stops a running workflow or deletes a saved workflow with only a post-hoc ui.notify(). A confirmation step prevents accidental data loss.

Current state

case 'stop':
  manager.stop(action.runId)     // immediate, no confirm
  ui.notify(`Stopped ${action.runId}`)
  break
case 'deleteSaved':
  storage.delete(action.savedName)  // immediate, no confirm

ctx.ui.confirm() already exists and is used in /workflows-models — infrastructure is in place.

Proposed change

case 'stop': {
  const ok = await ctx.ui.confirm(`Stop workflow "${run.name}"? This cannot be undone.`)
  if (!ok) break
  manager.stop(action.runId)
  break
}
case 'deleteSaved': {
  const ok = await ctx.ui.confirm(`Delete saved workflow "/${action.savedName}"?`)
  if (!ok) break
  storage.delete(action.savedName)
  pi.unregisterCommand(action.savedName)
  break
}

Also apply to pause with a lighter confirmation.

Files to change

• src/workflow-ui.ts — wrap stop, deleteSaved, pause with ctx.ui.confirm()