feat(tui): Batch 1 — event bus, AppState, two-panel layout, -T flag

[NikolaRHristov]

Batch 1 — Minimal TUI scaffold

This PR is the first incremental batch toward Run -T. Everything compiles against the existing codebase with zero behaviour change to the plain CLI path.

What changed

File	Change
Source/Struct/Event.rs	New — typed event enum (JobStarted, Line, JobProgress, JobFinished, IndexLockTimeout, AllDone)
Source/Struct/Tui.rs	New — AppState, DirState, Status enum, SPINNER frames, all nav/scroll helpers
Source/Fn/Tui/mod.rs	New — terminal init/restore RAII guard + main 100 ms tick loop
Source/Fn/Tui/Render.rs	New — two-panel ratatui layout (30 % dir list / 70 % log) + bottom status bar
Source/Fn/Tui/Input.rs	New — keyboard (↑↓ jk, PgUp/Dn, s, q, Ctrl-C) + mouse click dispatch
Source/Fn/Binary/Command/Sequential.rs	Modified — accepts Sender<Event>, removes all println!/eprintln!
Source/Fn/Binary/Command/Parallel.rs	Modified — same
Source/Fn/Binary/Command.rs	Modified — adds -T / --Tui clap flag
Source/Struct/Binary/Command/Option.rs	Modified — adds Tui: bool field
Source/Struct/Binary/Command.rs	Modified — creates mpsc channel, dispatches to Tui::Fn or plain printer
Source/Fn/mod.rs	Modified — pub mod Tui
Source/Struct/mod.rs	Modified — pub mod Event; pub mod Tui
Cargo.toml	Modified — adds ratatui = "0.29", crossterm = "0.28"

How to test locally

# CLI mode — identical behaviour to before
cargo run -- Cargo.toml -C "echo hello"

# TUI mode
cargo run -- -T Cargo.toml -C "cargo check"

# Parallel + TUI
cargo run -- -T -P Cargo.toml -C "cargo check"

Key design decisions

• Execution engines are now 100 % I/O-free — all output flows through mpsc::unbounded_channel::<Event>.
• The CLI printer is a zero-overhead tokio::spawn that calls println!/eprintln! — exact same observable output as before.
• ratatui/crossterm are unconditional dependencies (not feature-gated) to keep the PR minimal; feature-gating can be a follow-up.
• RAII TerminalGuard ensures the terminal is always restored even on panic.
• Spinner uses 10-frame Braille animation cycling on the 100 ms tick.

Next batches

• Batch 2 — re-run a directory on r keypress (daemon-like re-queue), exact click coordinates via area threading
• Batch 3 — command selector overlay (which commands to run per dir), filter/search in dir list
• Batch 4 — persist log to file, copy selected line to clipboard