feat: 实现会话配置与多轮上下文

- 新增 ConfigPanel 组件：TTS 开关、detail level、语言选择
- 新增 storage.ts：配置持久化到 localStorage
- useVisionSession：连接后自动发送 config，维护最近 10 轮对话历史
- App：齿轮按钮展开配置面板，HD 角标，TTS 播放联动 ttsEnabled

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/App.css

@@ -53,6 +53,26 @@ body {
   font-weight: 700;
 }
 
+.header-right {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.btn-icon {
+  background: none;
+  border: none;
+  font-size: 1.2rem;
+  cursor: pointer;
+  padding: 4px;
+  border-radius: 4px;
+  transition: background 0.2s;
+}
+
+.btn-icon:hover {
+  background: var(--color-surface);
+}
+
 .status {
   font-size: 0.85rem;
   padding: 4px 12px;
@@ -364,3 +384,67 @@ body {
 @keyframes spin {
   to { transform: rotate(360deg); }
 }
+
+/* ---- Config Panel ---- */
+
+.config-panel {
+  background: var(--color-surface);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius);
+  padding: 16px;
+  margin: 8px 0;
+}
+
+.config-panel__header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 12px;
+  font-weight: 600;
+}
+
+.config-panel__close {
+  background: none;
+  border: none;
+  color: var(--color-text-muted);
+  cursor: pointer;
+  font-size: 1rem;
+  padding: 2px 6px;
+}
+
+.config-panel__close:hover {
+  color: var(--color-text);
+}
+
+.config-row {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: 8px 0;
+  font-size: 0.9rem;
+}
+
+.config-row select,
+.config-row input[type="checkbox"] {
+  background: var(--color-bg);
+  color: var(--color-text);
+  border: 1px solid var(--color-border);
+  border-radius: 4px;
+  padding: 4px 8px;
+  font-size: 0.85rem;
+}
+
+/* ---- Detail Badge ---- */
+
+.detail-badge {
+  position: absolute;
+  top: 8px;
+  right: 8px;
+  background: rgba(37, 99, 235, 0.8);
+  color: white;
+  padding: 2px 8px;
+  border-radius: 4px;
+  font-size: 0.7rem;
+  font-weight: 700;
+  letter-spacing: 0.5px;
+}