feat: Add feature flag composable for 3D scanning

.env.production

@@ -1,3 +1,4 @@
 VITE_API_URL=https://radionica3d.me/api
 VITE_WS_URL=wss://radionica3d.me/ws
 VITE_GOOGLE_CLIENT_ID=254513580225-j893ad8nd2f2celd2thn1l42miqm9e7s.apps.googleusercontent.com
+VITE_ENABLE_3D_SCANNING=false

src/composables/useFeatureFlags.ts

@@ -0,0 +1,5 @@
+export function useFeatureFlags() {
+  return {
+    is3DScanningEnabled: import.meta.env.VITE_ENABLE_3D_SCANNING === 'true'
+  };
+}