feat: add interactive TUI control panel

[bsg62]

Summary

• Add opt-in --tui mode with ratatui/crossterm sidebar, log pane, footer hints, keyboard controls, and mouse-wheel log scrolling.
• Add TUI engine actor for server lifecycle, readiness polling, restart/stop-start, final command rerun, captured logs, and responsive quit/error handling.
• Preserve plain mode behavior while documenting the new --tui option.

Test Plan

• cargo test
• cargo clippy -- -D warnings
• cargo fmt -- --check
• cargo run -- --help
• ss -tlnp sport = :3000

Manual interactive cargo run -- --tui was not run in this non-interactive session.