Navi Code TUI: fix input box layout, command palette duplicate IDs, status renderer, and WS input loop ...

- clients/terminal/tui/widgets/input_box.py: switch Horizontal to Vertical with width: 100% for Input so it renders and accepts input in real terminals; add refresh on Input.Changed.
- clients/terminal/tui/screens/command_palette.py: remove fixed ListItem IDs to avoid DuplicateIds on fast filter.
- clients/terminal/tui/chat_model.py + renderers/status.py + widgets/chat_panel.py: render backend status events as dim system messages instead of raw dicts.
- clients/terminal/tui/ws_bridge.py: start NaviWebSocketClient.input_loop so enqueued user messages are actually sent to the backend.
- clients/terminal/tui/tui_app.py: focus InputBox synchronously in on_mount so typing works immediately.
- tests/clients/test_tui_app.py: regression test for visible input text.

Co-Authored-By: Claude <noreply@anthropic.com>

Navi Code: Phase 3 — Textual TUI skeleton (OpenCode-style) ...

- Add clients/terminal/tui package with micro-architecture:
  - events, context, chat_model, ws_bridge, permissions engine.
  - widgets: ChatPanel, StatusPanel, InputBox.
  - renderers: user/assistant messages, thinking, tool calls, errors,
    markdown, plain — registry-based and extensible.
  - slash commands: /help, /new, /sessions, /switch, /profile, /thinking,
    /compact, /quit — registry-based and extensible.
- Wire navi-code to launch TUI by default; keep click-CLI via --raw.
- Add textual>=0.70 dependency.
- Add TUI smoke tests via Textual Pilot.
- Add docs/plan_navi_code_tui.md with full Phase 4/5 roadmap.

Tests: 463 passed, 1 skipped (excluded unrelated websocket test).

Co-Authored-By: Claude <noreply@anthropic.com>