Phase 0: project scaffold

- Go module + chi server with embedded SPA serving and /api/health
- internal/config env loader (local-dev defaults; auth/copyleaks deferred)
- React 19 + Vite 6 + Tailwind v4 frontend with full Petal design tokens
- Frontend embedded into the binary via web/embed.go (go:embed all:dist)
- README dev workflow, .env.example, BUILD_PLAN progress tracker
- Verified end-to-end: binary serves health, embedded SPA, and SPA fallback

web/vite.config.ts

@@ -0,0 +1,21 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+import tailwindcss from '@tailwindcss/vite'
+
+// Dev: Vite serves the UI on :5173 and proxies /api to the Go backend on :8080.
+// Prod: `vite build` emits web/dist, which the Go binary embeds and serves itself.
+export default defineConfig({
+  plugins: [react(), tailwindcss()],
+  server: {
+    port: 5173,
+    proxy: {
+      '/api': 'http://localhost:8080',
+    },
+  },
+  build: {
+    outDir: 'dist',
+    // Keep false so the committed dist/.gitkeep placeholder survives builds —
+    // it's what lets `go build` compile on a fresh clone before any frontend build.
+    emptyOutDir: false,
+  },
+})