feat: Footswitch Modes — Stomp/Preset/Snapshot/Combo with scribble strips

Implements multi-mode footswitch system for the Helix Stadium-inspired pedal UI:

- Footswitch mode context provider with 4 modes: stomp, preset, snapshot, combo
- ModeSelector in status bar (collapsed cycling mode for mobile)
- Stomp mode: footswitches toggle individual blocks on/off, scribble strips show block name + status
- Preset mode: footswitches show Bank Up/Down + preset selection, scribble strips show preset name + number
- Snapshot mode: footswitches recall 8 snapshots, scribble strips show snapshot name
- Combo mode: first 4 stomp + bank nav + preset select + global bypass
- ScribbleStrip LCD component with LED indicator and double-tap support
- Double-tap gesture hook for secondary actions (tuner, snapshot save, etc.)
- FootswitchBar container with 8 capacitive-touch footswitch buttons and LED rings
- usePedalState hook (WebSocket + API polling, ported from frontend-react/App.jsx)
- Dark pedal theme CSS (Helix-inspired) with responsive mobile layout
- Full App.tsx rewrite with status bar, footswitch bar, tab bar, and all screens

ui/package.json

@@ -15,6 +15,7 @@
     "@radix-ui/react-slot": "^1.2.5",
     "@radix-ui/react-switch": "^1.3.0",
     "@radix-ui/react-tabs": "^1.1.14",
+    "@tailwindcss/vite": "^4.3.1",
     "react": "^19.2.6",
     "react-dom": "^19.2.6"
   },