refactor(mock): convert mock ids to numeric strings

lib/id.ts

@@ -1,6 +1,10 @@
 let counter = 0
 
 export function generateId(prefix: string) {
+  void prefix
   counter += 1
-  return `${prefix}-${Date.now()}-${counter}`
+
+  const now = Date.now().toString()
+  const suffix = counter.toString().padStart(3, "0")
+  return `${now}${suffix}`
 }