feat: comprehensive documentation and demo updates

- Update READMEs and docs across multiple languages
- Enhance interactive demos for Agent, LLM, VLM, Audio, Image Gen, Terminal, and Web Basics
- Add new appendix sections for Database and IDE intros
- Update VitePress config, theme, and utility scripts
- Clean up unused assets and components

docs/.vitepress/theme/components/appendix/git-intro/GitCommandDemo.vue

@@ -0,0 +1,153 @@
+<template>
+  <div class="command-demo">
+    <div class="panel">
+      <div class="terminal">
+        <div class="output">
+          <div v-for="(line, i) in output" :key="i" :class="line.type">
+            <span v-if="line.type === 'command'" class="prompt">$</span>
+            <span v-html="line.text"></span>
+          </div>
+          <div v-if="output.length === 0" class="welcome">
+            输入命令开始学习 Git
+          </div>
+        </div>
+        <div class="input-line">
+          <span class="prompt">$</span>
+          <input v-model="cmd" @keyup.enter="execute" placeholder="git status" class="cmd-input" />
+          <button @click="execute" class="run-btn">运行</button>
+        </div>
+      </div>
+
+      <div class="quick-cmds">
+        <button @click="runCmd('git init')" class="cmd-btn">初始化</button>
+        <button @click="runCmd('git status')" class="cmd-btn">状态</button>
+        <button @click="runCmd('git add .')" class="cmd-btn">添加</button>
+        <button @click="runCmd('git commit -m \'msg\'')" class="cmd-btn">提交</button>
+      </div>
+    </div>
+
+    <div class="info-box">
+      <p><strong>💡 常用命令:</strong> init → status → add → commit</p>
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { ref } from 'vue'
+
+const cmd = ref('')
+const output = ref([])
+
+const execute = () => {
+  const c = cmd.value.trim()
+  if (!c) return
+  
+  output.value.push({ type: 'command', text: c })
+  
+  if (c === 'git init') {
+    output.value.push({ type: 'success', text: 'Initialized empty Git repository' })
+  } else if (c === 'git status') {
+    output.value.push({ type: 'info', text: 'On branch main\nnothing to commit' })
+  } else if (c === 'git add .') {
+    output.value.push({ type: 'success', text: 'Files added to staging area' })
+  } else if (c.startsWith('git commit')) {
+    output.value.push({ type: 'success', text: '1 file committed' })
+  } else {
+    output.value.push({ type: 'error', text: 'Unknown command' })
+  }
+  
+  cmd.value = ''
+}
+
+const runCmd = (c) => {
+  cmd.value = c
+  execute()
+}
+</script>
+
+<style scoped>
+.command-demo {
+  border: 1px solid var(--vp-c-divider);
+  border-radius: 8px;
+  background-color: var(--vp-c-bg-soft);
+  padding: 1.5rem;
+  margin: 1rem 0;
+}
+
+.terminal {
+  background: #1f2937;
+  border-radius: 8px;
+  padding: 1rem;
+  margin-bottom: 1rem;
+  font-family: monospace;
+}
+
+.output {
+  min-height: 150px;
+  margin-bottom: 1rem;
+  color: #d1d5db;
+}
+
+.output .command { color: #10b981; }
+.output .success { color: #10b981; }
+.output .error { color: #ef4444; }
+.output .info { color: #60a5fa; }
+.output .welcome { color: #9ca3af; font-style: italic; }
+
+.input-line {
+  display: flex;
+  gap: 0.5rem;
+  align-items: center;
+}
+
+.prompt { color: #10b981; }
+
+.cmd-input {
+  flex: 1;
+  background: transparent;
+  border: none;
+  color: #d1d5db;
+  font-family: monospace;
+  font-size: 0.875rem;
+}
+
+.cmd-input:focus { outline: none; }
+
+.run-btn {
+  padding: 0.25rem 0.75rem;
+  background: #10b981;
+  color: white;
+  border: none;
+  border-radius: 4px;
+  cursor: pointer;
+  font-size: 0.75rem;
+}
+
+.quick-cmds {
+  display: flex;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.cmd-btn {
+  padding: 0.5rem 1rem;
+  border: 1px solid var(--vp-c-brand);
+  background: var(--vp-c-bg);
+  color: var(--vp-c-brand);
+  border-radius: 6px;
+  cursor: pointer;
+  font-size: 0.875rem;
+}
+
+.cmd-btn:hover { background: var(--vp-c-brand); color: var(--vp-c-bg); }
+
+.info-box {
+  padding: 1rem;
+  background: var(--vp-c-bg);
+  border-left: 4px solid var(--vp-c-brand);
+  border-radius: 4px;
+  margin-top: 1rem;
+}
+
+.info-box p { margin: 0; color: var(--vp-c-text-1); line-height: 1.6; }
+</style>