feat: Replace TUI with graphical macroquad UI and live panel preview

[WeekendSuperhero]

Summary

Replaces the ratatui terminal UI with a native graphical window (macroquad) that renders the physical Nanoleaf panel layout. The app now starts directly in visualizer mode with a real-time graphical representation of your device.

• Graphical panel rendering — Panels (hexagons, triangles, squares) are drawn to match the physical device layout with correct orientation, shape types, and controller positions
• Live color preview — Press Space to toggle real-time visualization of the colors being sent to the device, rendered directly on the panel shapes
• Album art integration — Press N to extract colors from the currently playing track's album artwork (Spotify via ScriptingBridge, Apple Music via iTunes Search API) with artwork displayed in the UI
• Removed ratatui dependency — No more terminal UI; the app is now a native windowed application
• All visualizer controls preserved — Same keybinds for gain, palette switching, effects, sorting, and panel reset
• DPI-aware text rendering — Uses camera_font_scale for sharp text on Retina displays
• Non-blocking album art fetching — All artwork downloads and color extraction happen on background threads

Changes

New

• app.rs — Complete rewrite as macroquad-based graphical app with panel rendering, floating HUD overlays, and help screen
• Shared color state (Arc<Mutex<HashMap<u16, [u8; 3]>>>) between visualizer thread and UI for live panel preview
• fetch_artwork_and_palette() — Single-fetch function that returns both artwork bytes and extracted palette to avoid race conditions
• Album art texture display in the UI (bottom-right corner)
• Proper bounding box calculation that accounts for panel radius (prevents edge panels from being clipped)
• Oklch→sRGB gamut clamping for accurate color reproduction

Removed

• event_handler.rs — Replaced by macroquad's built-in input handling
• ratatui dependency
• TUI effect list view and all related code (EffectList, Scroll, NlEffect, get_effect_list, play_effect, cur_effect_name)
• TuiConfig and colorful_effect_names config option
• osascript fallback for now-playing (replaced by ScriptingBridge-only + iTunes Search API)
• Pause/Resume visualizer messages (visualizer starts immediately)

Changed

• visualizer.rs — Writes display colors to shared HashMap after each frame for UI preview
• now_playing.rs — ScriptingBridge only (no subprocess spawning), iTunes Search API fallback for streaming track artwork
• config.rs — Removed tui_config section, silently ignores legacy config for backwards compatibility
• main.rs — Launches macroquad window instead of ratatui terminal
• README.md — Rewritten to reflect the graphical app with new screenshot and demo GIF

Test plan

• Launch with a connected Nanoleaf device — window shows panel layout
• Press Space — panels show live visualization colors matching the device
• Press 1-0 — palette switches, colors update on device and in preview
• Press E — cycles through Spectrum / Energy Wave / Pulse effects
• Press N with Spotify or Apple Music playing — album art appears, palette changes to extracted colors
• Change tracks — artwork and palette auto-update after ~3 seconds
• Press ? — help overlay appears with all keybinds
• Press -/+ — gain adjusts (visual only, not audio volume)
• Press A/P/S — sorting controls update
• Window resize — panels rescale to fit
• ESC — clean shutdown, device turns off