fix: declare process global so tsc build gate passes (pre-existing)

vite.config.ts

@@ -1,5 +1,9 @@
 import { defineConfig } from 'vitest/config';
 
+// Minimal Node global declaration so tsc resolves `process.env` below without pulling in
+// the full @types/node package (tsconfig pins `types` to vitest/globals only).
+declare const process: { env: Record<string, string | undefined> };
+
 export default defineConfig({
   // Dev-only: proxy the CNC MJPEG camera so the page can load it via a
   // same-origin relative path (`/camera/...`), exactly as nginx does in