Effects engine, SVG/VU/silhouette categories, pad bank, MP4 recording, dual-window UI

- Parametric effect engine: 23 shader families × palettes × variants (~2300 presets)
  with a filterable library and an effect sequence (auto-cycle by time or beat).
- Effect categories: fractals/abstract, dancing silhouettes, SVG/Image source
  (loads any SVG/image as a recolourable audio-reactive effect; 50+ bundled CC0 SVGs),
  and VU-Meter (32-band spectrum bars, analogue needle, stereo LEDs).
- Dual-window architecture: control panel + fullscreen output on an external display
  (reliable via simple-fullscreen); tabbed control UI (Audio, Effetti, Pad, Immagini,
  Testo, Registra, Schermo).
- Audio: file playback + live input + output device selection, per-band visual EQ,
  audio playlist (reorder, hotkeys, per-track play/pause, repeat).
- Pad bank: 5×4 launchpad with persistent assignments; pressing a pad stops the current.
- Overlays: slideshow images (resizable), two freely positioned/resizable logos,
  scrolling ticker text.
- MP4 recording of the composited output (visual + overlays + audio) via MediaRecorder
  + ffmpeg, with selectable aspect ratios (16:9, 9:16, 1:1, 4:3, 3:4, 21:9).
- App icon (.icns) and dock icon; author Dj LuZa.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

preload.js

@@ -13,6 +13,8 @@ contextBridge.exposeInMainWorld('djv', {
   report: (msg) => ipcRenderer.send('rpt', msg),
   onReport: (cb) => ipcRenderer.on('rpt', (_e, m) => cb(m)),
   // Display management (control window).
+  // Bundled svg/ folder, read in the main process, as same-origin data URLs.
+  listBuiltinSvgs: () => ipcRenderer.invoke('svg:listBuiltin'),
   // Resolve a dropped/picked File to its absolute filesystem path.
   pathForFile: (file) => {
     try { return webUtils.getPathForFile(file); }
@@ -20,5 +22,13 @@ contextBridge.exposeInMainWorld('djv', {
   },
   listDisplays: () => ipcRenderer.invoke('displays:list'),
   moveOutputTo: (id) => ipcRenderer.invoke('output:moveTo', id),
-  toggleOutputFullscreen: () => ipcRenderer.invoke('output:toggleFullscreen')
+  toggleOutputFullscreen: () => ipcRenderer.invoke('output:toggleFullscreen'),
+  // Recording (output streams chunks to main, which muxes/transcodes to MP4).
+  recStart: () => ipcRenderer.invoke('rec:start'),
+  recChunk: (bytes) => ipcRenderer.send('rec:chunk', bytes),
+  recStop: (opts) => ipcRenderer.invoke('rec:stop', opts),
+  openRecordingsFolder: () => ipcRenderer.invoke('rec:openFolder'),
+  // Pad bank persistence.
+  loadPads: () => ipcRenderer.invoke('pads:load'),
+  savePads: (data) => ipcRenderer.invoke('pads:save', data)
 });