feat(appendix): 添加多个交互式演示组件，完善 AI/Infra 等章节内容

- 新增 Vibe Coding 全栈相关演示组件 (DeveloperSkillShift, FrontendTriad, BackendCore 等)
- 新增 RAG 相关组件 (RAGPipeline, ChunkingStrategy, Retrieval 等)
- 新增 Embedding & Vector 相关组件 (EmbeddingConcept, VectorSimilarity 等)
- 新增 AI Native App 设计组件 (AINativeArch, PromptDesign 等)
- 新增 Infrastructure as Code 组件 (IaCConcept, TerraformWorkflow 等)
- 新增 DNS & HTTPS 演示组件 (DnsResolution, HttpsHandshake 等)
- 新增 Model Finetuning 组件 (FinetuningPipeline 等)
- 更新多个章节的 markdown 内容，集成交互式演示

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

@@ -0,0 +1,128 @@
+<template>
+  <div class="language-selection-demo">
+    <div class="demo-header">
+      <span class="title">语言选择指南</span>
+      <span class="subtitle">根据目标选语言</span>
+    </div>
+
+    <div class="selection-grid">
+      <div v-for="item in selections" :key="item.goal" class="selection-card">
+        <div class="goal-name">{{ item.goal }}</div>
+        <div class="goal-desc">{{ item.desc }}</div>
+        <div class="goal-langs">
+          <span class="lang-label">推荐：</span>
+          <span v-for="lang in item.langs" :key="lang" class="lang-tag">{{ lang }}</span>
+        </div>
+      </div>
+    </div>
+
+    <div class="info-box">
+      <strong>核心原则：</strong>语言只是工具，重要的是解决问题的能力。先精通一门，再触类旁通。
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { ref } from 'vue'
+
+const selections = ref([
+  { goal: 'Web 前端', desc: '网页、小程序、H5', langs: ['JavaScript', 'TypeScript'] },
+  { goal: 'Web 后端', desc: 'API 服务、业务系统', langs: ['Node.js', 'Go', 'Java', 'Python'] },
+  { goal: '移动端', desc: 'iOS / Android 应用', langs: ['Swift', 'Kotlin', 'Flutter'] },
+  { goal: 'AI / 数据科学', desc: '机器学习、数据分析', langs: ['Python'] },
+  { goal: '系统编程', desc: '操作系统、嵌入式', langs: ['C', 'C++', 'Rust'] },
+  { goal: '快速原型', desc: '脚本、自动化、小工具', langs: ['Python', 'Shell'] }
+])
+</script>
+
+<style scoped>
+.language-selection-demo {
+  border: 1px solid var(--vp-c-divider);
+  border-radius: 8px;
+  background: var(--vp-c-bg-soft);
+  padding: 1rem 1.2rem;
+  margin: 1rem 0;
+}
+
+.demo-header {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  margin-bottom: 1rem;
+  padding-bottom: 0.75rem;
+  border-bottom: 1px solid var(--vp-c-divider);
+}
+
+.title {
+  font-size: 0.95rem;
+  font-weight: 600;
+  color: var(--vp-c-text-1);
+}
+
+.subtitle {
+  font-size: 0.78rem;
+  color: var(--vp-c-text-3);
+}
+
+.selection-grid {
+  display: grid;
+  grid-template-columns: repeat(2, 1fr);
+  gap: 0.5rem;
+}
+
+.selection-card {
+  padding: 0.6rem 0.75rem;
+  background: var(--vp-c-bg);
+  border: 1px solid var(--vp-c-divider);
+  border-radius: 6px;
+}
+
+.goal-name {
+  font-size: 0.82rem;
+  font-weight: 600;
+  color: var(--vp-c-text-1);
+  margin-bottom: 0.15rem;
+}
+
+.goal-desc {
+  font-size: 0.7rem;
+  color: var(--vp-c-text-3);
+  margin-bottom: 0.35rem;
+}
+
+.goal-langs {
+  display: flex;
+  align-items: center;
+  flex-wrap: wrap;
+  gap: 0.25rem;
+}
+
+.lang-label {
+  font-size: 0.68rem;
+  color: var(--vp-c-text-3);
+}
+
+.lang-tag {
+  font-size: 0.68rem;
+  padding: 0.15rem 0.4rem;
+  background: var(--vp-c-bg-soft);
+  border-radius: 3px;
+  color: var(--vp-c-brand-1);
+}
+
+.info-box {
+  margin-top: 1rem;
+  padding: 0.75rem;
+  background: var(--vp-c-bg);
+  border-radius: 6px;
+  font-size: 0.8rem;
+  color: var(--vp-c-text-2);
+  border-left: 3px solid var(--vp-c-brand-1);
+}
+
+@media (max-width: 640px) {
+  .selection-grid {
+    grid-template-columns: 1fr;
+  }
+}
+</style>