Replace fragile Vite ONNX plugin with standard solution

[Lucasmind]

Priority: LOW

Problem

The custom serveOnnxFiles() Vite plugin manually parses URLs to serve ONNX WASM files. This is fragile and could break if the path structure of the onnxruntime-web package changes in future versions.

Current Implementation

// vite.config.js - serveOnnxFiles() plugin
// Manually intercepts requests and serves .wasm files from node_modules

Suggested Fix

Investigate using standard Vite WASM plugins:

• vite-plugin-wasm
• @aspect-build/rules_wasm
• Or a simpler approach: copy WASM files to public/ at build time

// Option: Copy plugin
{
  name: 'copy-onnx-wasm',
  buildStart() {
    // Copy ort-wasm*.wasm files to public/
  }
}

Considerations

• Must maintain compatibility with vad-web (CJS module, see CLAUDE.md)
• talkinghead uses dynamic workers and MUST stay excluded from optimizeDeps
• After any changes: delete node_modules/.vite cache and test thoroughly

Files Affected

• frontend/vite.config.js