refactor(mock): remove lib/mock fixtures and empty stores

store/comments.ts

@@ -1,5 +1,4 @@
 import { generateId } from "@/lib/id"
-import { mockComments } from "@/lib/mock"
 import type { Comment, User } from "@/lib/types"
 import { create } from "zustand"
 
@@ -10,7 +9,7 @@ interface CommentState {
 }
 
 export const useCommentStore = create<CommentState>((set) => ({
-  comments: mockComments,
+  comments: [],
   addComment: (postId, author, content) => {
     const normalizedContent = content.trim()
     if (!normalizedContent) return null