docs: add VitePress documentation site

- Add docs directory with VitePress configuration
- Add GitHub Actions workflow for docs build and deploy
- Support bilingual (English/Chinese) documentation
- Include search, custom theme, and responsive design

docs/.vitepress/theme/components/CopyCodeButton.vue

@@ -0,0 +1,135 @@
+<script setup lang="ts">
+import { ref } from 'vue'
+
+const props = defineProps<{
+  code: string
+}>()
+
+const emit = defineEmits<{
+  (e: 'copy'): void
+}>()
+
+const copied = ref(false)
+
+const copyToClipboard = async () => {
+  try {
+    await navigator.clipboard.writeText(props.code)
+    copied.value = true
+    emit('copy')
+    setTimeout(() => {
+      copied.value = false
+    }, 2000)
+  } catch (err) {
+    console.error('Failed to copy:', err)
+  }
+}
+
+// Also handle Ctrl+C
+const handleKeydown = (e: KeyboardEvent) => {
+  if (e.ctrlKey && e.key === 'c') {
+    copyToClipboard()
+  }
+}
+</script>
+
+<template>
+  <button
+    class="copy-code-button"
+    :class="{ copied }"
+    :aria-label="copied ? 'Copied!' : 'Copy code'"
+    :title="copied ? 'Copied!' : 'Copy code (Ctrl+C)'"
+    @click="copyToClipboard"
+    @keydown="handleKeydown"
+  >
+    <svg v-if="!copied" class="icon copy-icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+      <rect x="9" y="9" width="13" height="13" rx="2" ry="2"/>
+      <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"/>
+    </svg>
+    <svg v-else class="icon check-icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+      <polyline points="20 6 9 17 4 12"/>
+    </svg>
+    <span v-if="copied" class="copy-feedback">Copied!</span>
+  </button>
+</template>
+
+<style scoped>
+.copy-code-button {
+  position: absolute;
+  top: 12px;
+  right: 12px;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  padding: 6px 12px;
+  border: 1px solid var(--vp-c-border);
+  border-radius: var(--vp-radius-md);
+  background: var(--vp-c-bg);
+  color: var(--vp-c-text-2);
+  font-size: var(--vp-font-size-sm);
+  cursor: pointer;
+  opacity: 0;
+  transition: all var(--vp-transition-color);
+  z-index: 10;
+}
+
+.copy-code-button:hover {
+  background: var(--vp-c-bg-soft);
+  color: var(--vp-c-text-1);
+  border-color: var(--vp-c-primary);
+}
+
+.copy-code-button.copied {
+  background: var(--vp-c-secondary-500);
+  color: white;
+  border-color: var(--vp-c-secondary-500);
+}
+
+.copy-code-button .icon {
+  width: 16px;
+  height: 16px;
+}
+
+.copy-feedback {
+  position: absolute;
+  top: 100%;
+  right: 0;
+  margin-top: 4px;
+  padding: 4px 8px;
+  background: var(--vp-c-bg);
+  border: 1px solid var(--vp-c-border);
+  border-radius: var(--vp-radius-md);
+  font-size: 12px;
+  white-space: nowrap;
+  animation: fadeIn 0.2s ease;
+}
+
+@keyframes fadeIn {
+  from {
+    opacity: 0;
+    transform: translateY(-4px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+/* Show button on code block hover */
+div[class*='language-']:hover .copy-code-button,
+.copy-code-button:focus {
+  opacity: 1;
+}
+
+@media (max-width: 768px) {
+  .copy-code-button {
+    opacity: 1;
+    top: 8px;
+    right: 8px;
+    padding: 8px;
+  }
+
+  .copy-feedback {
+    display: none;
+  }
+}
+</style>