v0.1.3

Bundle MediaPipe locally and surface real init errors

Packaged WebView2 was failing to initialize the Face Landmarker when
fetching the WASM/model from jsdelivr + googleapis — the error came
through to our handler as a non-Error object, so the UI degraded to
the unhelpful "failed to start face tracker" fallback.

- scripts/setup-mediapipe.mjs runs as part of pnpm build (and pnpm dev),
  copies the tasks-vision WASM out of node_modules into public/
  mediapipe/wasm, and downloads face_landmarker.task into the same
  folder. Vite then publishes the lot into dist/, so the packaged
  app loads everything from app:// rather than the network.
- HeadLandmarker points at the local paths, tries the GPU delegate
  first and falls back to CPU automatically if GPU compilation throws.
  Either path failing now surfaces a real message instead of a
  swallowed exception.
- Calibration's catch handler properly stringifies whatever MediaPipe
  threw (Error / string / object with .message / JSON) and logs the
  raw value to the console so we can still see it if the stringified
  form is opaque.

Installer grows ~37 MB (WASM + model) — worth it for offline first-
run and to remove a fragile remote dependency. Bump to 0.1.3.