fix(gro-405): devFetch interceptor runs in deployed dev builds

Replace build-time `import.meta.env.DEV` guard with a runtime check
using localStorage presence of a dev user. This ensures the
X-Dev-User-Id header is injected in deployed dev pods (groombook.dev),
not just during local `vite dev`.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/lib/devFetch.ts

@@ -9,8 +9,9 @@ const originalFetch = window.fetch;
  * Intentionally mutates window.fetch — this is dev-only (AUTH_DISABLED=true).
  */
 export function installDevFetchInterceptor() {
-  // In production, Better-Auth handles auth via cookies — no interception needed
-  if (!import.meta.env.DEV) return;
+  // Only install if a dev user is selected (localStorage check, not build-time flag).
+  // This ensures the interceptor runs in deployed dev builds, not just `vite dev`.
+  if (!getDevUser()) return;
 
   window.fetch = function (input: RequestInfo | URL, init?: RequestInit) {
     const user = getDevUser();