Fix: compute __dirname in vite.config.ts (undefined under ESM)

`__dirname` is undefined in ESM modules, so `path.resolve(__dirname, "./src")`
silently produced a bad path in Docker. Locally it happened to work (some
Node interop), but the Docker stage hit a clear error: "Could not load
/web/src/lib/utils ... ENOENT". Use fileURLToPath(import.meta.url).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/vite.config.ts

@@ -1,9 +1,14 @@
-import path from "path";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
 
-// During dev (`pnpm dev`), Vite serves on :5173 and proxies /api + /mcp + /health
-// to the FastAPI server on :8765 (or PORT env var).
+// `__dirname` is undefined in ESM; compute it ourselves so the alias
+// resolves correctly under both local Node and the Docker build.
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+// During dev (`npm run dev`), Vite serves on :5173 and proxies /api +
+// /mcp + /health to the FastAPI server on :8765 (or BACKEND_PORT env).
 const BACKEND_PORT = process.env.BACKEND_PORT || "8765";
 
 export default defineConfig({