Move ONNX model to GitHub Releases to eliminate Vercel bandwidth costs

The 93MB maia_rapid.onnx file was served from public/ causing ~$150/month
in Vercel Fast Data Transfer charges. Move it to a GitHub Release asset
(free, served with CORS headers) and remove from git tracking.

- Update model URL to GitHub Releases download URL (with NEXT_PUBLIC_MAIA_MODEL_URL env var override)
- Remove public/maia2/*.onnx from git via .gitignore

To complete: create a GitHub Release tagged `models-v1` and upload
maia_rapid.onnx as a release asset.

https://claude.ai/code/session_01T73Yphu4y2U3c3ctCcHVPf

Author: claude

.gitignore

@@ -36,3 +36,6 @@ yarn-error.log*
 
 # typescript
 *.tsbuildinfo
+
+# ONNX model weights - hosted on GitHub Releases, not committed to the repo
+/public/maia2/*.onnx

public/maia2/maia_rapid.onnx

@@ -31,7 +31,9 @@ export const MaiaEngineContextProvider: React.FC<{ children: ReactNode }> = ({
 
   const maia = useMemo(() => {
     const model = new Maia({
-      model: '/maia2/maia_rapid.onnx',
+      model:
+        process.env.NEXT_PUBLIC_MAIA_MODEL_URL ??
+        'https://github.com/CSSLab/maia-platform-frontend/releases/download/models-v1/maia_rapid.onnx',
       setStatus: setStatus,
       setProgress: setProgress,
       setError: setError,