feat: update documentation and component demos for backend layered architecture

- Add new LanguageScopeDemo component for backend languages overview
- Refactor and simplify existing demo components (ControllerLayerDemo, DtoFlowDemo, DependencyDirectionDemo)
- Update .gitignore to exclude .claude/skills directory
- Modify backend-related sections in documentation from "后端与全栈" to "后端开发"
- Add new backend layered architecture demo components (CleanArchitectureDemo, DependencyDirectionDemo)
- Improve documentation structure and content for stage-3 core skills
- Fix component initialization timing in CompileVsInterpretDemo and RateLimiterDemo
- Add design style prompt reference in frontend documentation

docs/.vitepress/theme/components/appendix/computer-fundamentals/CompileVsInterpretDemo.vue

@@ -47,12 +47,17 @@
 </template>
 
 <script setup>
-import { ref, onUnmounted } from 'vue'
+import { ref, onMounted, onUnmounted } from 'vue'
 
 const selected = ref(0)
 const visibleSteps = ref(0)
 let timer = null
 
+onMounted(() => {
+  // 组件挂载后开始动画，避免模块加载时启动定时器导致 build 卡住
+  selectMode(0)
+})
+
 onUnmounted(() => {
   if (timer) clearInterval(timer)
 })
@@ -117,8 +122,6 @@ const modes = [
     langs: ['JavaScript (V8)', 'Java (JVM)', 'C# (.NET)']
   }
 ]
-
-selectMode(0)
 </script>
 
 <style scoped>