feat(tui): add auto-accept mode for permission requests

Add a toggleable auto-accept mode that automatically accepts all incoming
permission requests with a 'once' reply. This is useful for users who want
to streamline their workflow when they trust the agent's actions.

Changes:
- Add permission_auto_accept keybind (default: shift+tab) to config
- Remove default for agent_cycle_reverse (was shift+tab)
- Add auto-accept logic in sync.tsx to auto-reply when enabled
- Add command bar action to toggle auto-accept mode (copy: "Toggle autoaccept permissions")
- Add visual indicator showing 'auto-accept' when active
- Store auto-accept state in KV for persistence across sessions