新增前后端AI聊天模块，包括流式对话、配置管理和UI组件优化。

frontend/src/components/ui/BaseModal.vue

@@ -0,0 +1,68 @@
+<script setup lang="ts">
+defineProps<{
+  show: boolean
+}>()
+
+const emit = defineEmits<{
+  close: []
+}>()
+</script>
+
+<template>
+  <Teleport to="body">
+    <Transition name="modal">
+      <div v-if="show" class="modal-overlay" @click.self="emit('close')">
+        <div class="modal-panel">
+          <slot />
+        </div>
+      </div>
+    </Transition>
+  </Teleport>
+</template>
+
+<style scoped>
+.modal-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 1000;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(26, 26, 46, 0.3);
+  backdrop-filter: blur(6px);
+}
+
+.modal-panel {
+  background: var(--paper-50);
+  border: 1px solid var(--paper-200);
+  border-radius: var(--radius-lg);
+  padding: var(--space-xl);
+  max-width: 560px;
+  width: 90%;
+  max-height: 85vh;
+  overflow-y: auto;
+  box-shadow: var(--shadow-lg);
+}
+
+/* 转场动画 */
+.modal-enter-active {
+  transition: opacity var(--duration-normal) ease;
+}
+
+.modal-leave-active {
+  transition: opacity var(--duration-fast) ease;
+}
+
+.modal-enter-from,
+.modal-leave-to {
+  opacity: 0;
+}
+
+.modal-enter-active .modal-panel {
+  animation: scaleIn var(--duration-normal) var(--ease-out-back) both;
+}
+
+.modal-leave-active .modal-panel {
+  animation: scaleIn var(--duration-fast) ease reverse both;
+}
+</style>