Rewrite from Go + vanilla JS to Python (FastAPI) + React (TypeScript)

- Backend: Python 3.12 with FastAPI, SQLAlchemy, boto3
- Frontend: React 18 with TypeScript, Vite build tooling
- Updated Dockerfile for multi-stage Node + Python build
- Updated CI pipeline for Python backend
- Removed old Go code (cmd/, internal/, go.mod, go.sum)
- Updated README with new tech stack documentation

frontend/vite.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+export default defineConfig({
+  plugins: [react()],
+  server: {
+    proxy: {
+      '/api': 'http://localhost:8080',
+      '/health': 'http://localhost:8080',
+      '/grove': 'http://localhost:8080',
+    }
+  }
+})