refactor: clean up codebase and add new features

Replace SCSS variable usages with explicit pixel/hex values for consistent styling across all components
Fix broken template syntax including missing class spaces and incorrect closing tags
Migrate constant and API imports to centralized @/constants and @/api modules
Add new utility classes: IdUtils, CallbackUtils, and TimerUtils
Add new chat conversation API endpoints for recent conversations and message lists
Add new Discovery page components (FindTabs, QuickQuestions, CardSwiper) and their styles
Update app store config to use environment variables for base API and WebSocket URLs
Add new selected tab icon assets

src/pages/home/components/AnswerComponent/index.vue

@@ -31,14 +31,14 @@
 <script setup>
 import { defineProps, computed, watch, onBeforeUnmount } from "vue";
 
-import ChatMarkdown from "./ChatMarkdown/index.vue";
+import ChatMarkdown from "../ChatMarkdown/index.vue";
 import ChatLoading from "./ChatLoading/index.vue";
 import StreamManager from '@/utils/StreamManager.js';
 import {
   getLongTextPredivText,
   getLongTextValue,
   hasLongTextExtraSections,
-} from "@/utils/longTextCard";
+} from "@/constants/longTextCard";
 
 // 直接根据文字长度判断，超过约100个字符认为会溢出（约3行）
 const props = defineProps({