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/tsconfig.json

@@ -5,9 +5,15 @@
     "moduleResolution": "bundler",
     "strict": true,
     "noEmit": true,
-    "skipLibCheck": true,
     "types": ["vitest/globals"],
-    "lib": ["ES2022"]
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "paths": {
+      "$lib/*": ["src/lib/*"],
+      "$app/*": [".svelte-kit/types/$app/*"],
+      "$types": [".svelte-kit/types/*"]
+    },
+    "baseUrl": "."
   },
-  "include": ["src/**/*.ts"]
+  "include": ["src/**/*.ts", "src/**/*.svelte"],
+  "exclude": ["node_modules"]
 }