feat: 扩展 Settings 页面功能

- 添加解析设置配置
- 优化模型设置表单
- 添加更多样式配置

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/views/settings/modelSettings.css

@@ -233,6 +233,10 @@
   color: white;
 }
 
+.add-model-dialog :deep(.el-input__inner::placeholder) {
+  color: #6b7280;
+}
+
 .add-model-dialog :deep(.el-select) {
   width: 100%;
 }
@@ -246,6 +250,10 @@
   color: white;
 }
 
+.add-model-dialog :deep(.el-select .el-input__inner::placeholder) {
+  color: #6b7280;
+}
+
 .add-model-dialog :deep(.el-select-dropdown) {
   background-color: #1a1a24;
   border: 1px solid #2a2a3a;