TUI v2 2.2: Command box + slash-command parser (MVP)

[tomdps]

Summary

Implement Issue 2.2 from the TUI v2 plan: add a global command/input box and slash-command parser, with MVP command set and UI feedback.

Scope

• Global input component available from any view.
• Parse rules:
  • /... => command
  • otherwise => plain-text task description (stubbed for now)
• Implement MVP commands:
  • /help
  • /monitor
  • /issue <ref> (stubbed; full orchestration in Milestone 3)
  • /provider <name>
  • /quit
• Display command output in a status/toast area.

Non-scope

• No cluster execution (Milestone 3).
• No full CLI parity (Issue 2.3).
• No visual polish beyond basic layout for input + output area.

Implementation Plan

1. Add a shared input component at the app shell level and wire it to current view state.
2. Implement a simple parser that classifies input as command vs plain text.
3. Add a command dispatcher with handlers for the MVP commands.
4. Wire provider switching to session state and reflect it in the UI indicator.
5. Add a lightweight output/toast area to show command results/errors.

Tests

• Parser unit tests for / commands and plain text.
• Command handler tests for /provider, /monitor, /help, /quit.
• Smoke test: input renders and dispatches from multiple views (Ink testing if available).

Acceptance Criteria

• Commands work from any view.
• Provider switches update a session state indicator.
• Command output is visible in the UI (toast/status).
• /issue <ref> is stubbed with a clear placeholder message (until Milestone 3).

Dependencies

• Depends on Issue 2.1 (view router + view stack).

References

• docs/tui-v2/IMPLEMENTATION_PLAN.md (Issue 2.2)
• docs/tui-v2/PRD.md (Commands / input model)

[tomdps]

Implemented in PR #184