feat(media): add image / video / audio surfaces with unified od media generate dispatcher

Extends Open Design from web-only to a multi-modal creation tool. The
unifying contract is one code-agent loop driven by skills + project
metadata + prompt constraints; for non-web surfaces the agent shells
out to a single dispatcher (`od media generate`) that the daemon
routes per (surface, model).

- Types: new Surface union, MediaAspect / AudioKind, image/video/audio
  ProjectKind + ProjectMetadata fields, video/audio ProjectFileKind.
- NewProjectPanel: top-level surface picker + Image / Video / Audio
  forms with model, aspect, length, duration, voice, audio-kind pickers.
- ExamplesTab + DesignSystemsTab: surface filter row that scopes
  before mode / scenario / category filters.
- FileViewer / FileWorkspace: native <video> and <audio> previews and
  matching tab icons.
- Daemon: parses `od.surface` and `> Surface:` blockquotes; recognises
  mp4 / webm / mov / mp3 / wav / ogg / m4a / flac extensions; spawns
  agents with OD_BIN / OD_DAEMON_URL / OD_PROJECT_ID / OD_PROJECT_DIR
  env so any code-agent CLI with shell access can call the dispatcher.
- daemon/media.js + daemon/media-models.js: surface-agnostic dispatcher
  with stub providers that emit deterministic placeholder bytes
  (1x1 PNG, valid mp4 ftyp, mp3 frame / silent WAV) so the framework
  works without API keys; real provider integrations slot in later.
- daemon/cli.js: `od media generate --surface ... --model ...`
  subcommand routes to POST /api/projects/:id/media/generate and
  prints one JSON line for the agent to parse.
- prompts/media-contract.ts: hard contract pinned LAST in the system
  prompt for image/video/audio surfaces — env vars, exact invocation,
  registered model IDs per surface, six workflow rules. system.ts
  metadata block updated to point at the contract.
- Seed skills: image-poster, video-shortform, audio-jingle each ship a
  SKILL.md with `mode/surface: image|video|audio` and a stylized
  example.html preview, and instruct the agent to dispatch via the
  contract.

Made-with: Cursor

daemon/design-systems.js

@@ -29,6 +29,11 @@ export async function listDesignSystems(root) {
         category: extractCategory(raw) ?? 'Uncategorized',
         summary: summarize(raw),
         swatches: extractSwatches(raw),
+        // Optional `> Surface: image|video|audio` blockquote line. Most
+        // existing systems target the web surface and don't declare it;
+        // we default to 'web' so the right-side filter classifies them
+        // correctly.
+        surface: extractSurface(raw),
         body: raw,
       });
     } catch {
@@ -67,6 +72,14 @@ function extractCategory(raw) {
   return m?.[1];
 }
 
+const KNOWN_SURFACES = new Set(['web', 'image', 'video', 'audio']);
+function extractSurface(raw) {
+  const m = /^>\s*Surface:\s*(.+?)\s*$/im.exec(raw);
+  if (!m) return 'web';
+  const v = m[1].trim().toLowerCase();
+  return KNOWN_SURFACES.has(v) ? v : 'web';
+}
+
 // Strip boilerplate like "Design System Inspired by Cohere" → "Cohere" so
 // the picker dropdown reads cleanly. Hand-authored titles that don't match
 // the pattern (e.g. "Neutral Modern") pass through unchanged.