fix(mongoose): fall back to process.env when run outside Nitro

connectDB() called useRuntimeConfig() unconditionally — works inside
the Nuxt/Nitro runtime but throws ReferenceError for standalone Node
scripts (seed-members.js, seed-tags.js, etc.). CI exposed this when
trying to run seed-all.js. Detect the auto-import and fall back to
process.env when it's not available; preserves Nitro behavior.

server/utils/mongoose.js

@@ -7,7 +7,10 @@ export const connectDB = async () => {
     return;
   }
 
-  const MONGODB_URI = useRuntimeConfig().mongodbUri;
+  const MONGODB_URI =
+    typeof useRuntimeConfig === 'function'
+      ? useRuntimeConfig().mongodbUri
+      : process.env.NUXT_MONGODB_URI || process.env.MONGODB_URI;
 
   try {
     await mongoose.connect(MONGODB_URI, {