Gate B: SvelteKit capture→mask→numbers→review UI with deterministic pipeline

- Scaffold SvelteKit app (svelte.config.js, vite.config.ts, app.html, app.d.ts)
- Build full capture flow: photo input → mask overlay + 4 knobs → axis overlay
  + rotation → length/thickness/SKU inputs → review + upload to /api/v1/slabs
- Uses existing lib/pipeline/* pure modules (mask, axis, units, crop, pricing, types)
- Uses existing validation/sku.ts for SKU validation
- Svelte 5 runes ($state, $effect, $derived) for reactive state
- Canvas-based rendering for mask overlay, axis visualization, and 3:4 crop preview
- Dockerfile updated for Vite production build with static Node server on :80
- All 54 existing tests pass, build succeeds

frontend/package.json

@@ -4,12 +4,21 @@
   "version": "0.0.0",
   "type": "module",
   "scripts": {
+    "dev": "vite dev",
+    "build": "vite build",
+    "preview": "vite preview",
     "test": "vitest run",
     "test:watch": "vitest"
   },
   "devDependencies": {
+    "@sveltejs/adapter-static": "^3.0.6",
+    "@sveltejs/kit": "^2.16.0",
+    "@sveltejs/vite-plugin-svelte": "^5.0.3",
     "pngjs": "^7.0.0",
+    "svelte": "^5.0.0",
+    "svelte-check": "^4.1.1",
     "typescript": "^5.6.3",
+    "vite": "^6.0.7",
     "vitest": "^2.1.4"
   }
 }