重大重构：从字段替换切换到完整配置文件切换系统

- 实现基于文件重命名的供应商切换机制，支持完整settings.json配置切换
- 移除所有向后兼容代码，简化为纯JSON配置模式
- 添加导入当前配置功能，解决首次使用时配置丢失问题
- 移除描述字段，简化用户界面
- 完整的错误处理和回滚机制确保配置安全
- 清理所有调试代码，优化代码质量

src/renderer/components/AddProviderModal.css

@@ -16,7 +16,7 @@
   border-radius: 8px;
   padding: 2rem;
   width: 90%;
-  max-width: 500px;
+  max-width: 600px;
   max-height: 90vh;
   overflow-y: auto;
   box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
@@ -55,6 +55,7 @@
 .preset-buttons {
   display: flex;
   gap: 0.5rem;
+  flex-wrap: wrap;
 }
 
 .preset-btn {
@@ -84,7 +85,8 @@
   font-weight: 500;
 }
 
-.form-group input {
+.form-group input,
+.form-group textarea {
   width: 100%;
   padding: 0.625rem;
   border: 1px solid #ddd;
@@ -92,9 +94,16 @@
   font-size: 0.95rem;
   transition: border-color 0.2s;
   background: white;
+  box-sizing: border-box;
 }
 
-.form-group input:focus {
+.form-group textarea {
+  resize: vertical;
+  min-height: 200px;
+}
+
+.form-group input:focus,
+.form-group textarea:focus {
   outline: none;
   border-color: #3498db;
 }
@@ -134,48 +143,6 @@
   background: #229954;
 }
 
-.password-input-wrapper {
-  position: relative;
-  display: flex;
-  align-items: center;
-}
-
-.password-input-wrapper input {
-  padding-right: 2.5rem;
-}
-
-.password-toggle {
-  position: absolute;
-  right: 0.5rem;
-  top: 50%;
-  transform: translateY(-50%);
-  padding: 0.375rem;
-  background: none;
-  border: none;
-  cursor: pointer;
-  color: #7f8c8d;
-  transition: color 0.2s;
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  width: 32px;
-  height: 32px;
-}
-
-.password-toggle svg {
-  width: 20px;
-  height: 20px;
-  stroke-width: 2;
-}
-
-.password-toggle:hover {
-  color: #3498db;
-}
-
-.password-toggle:focus {
-  outline: none;
-}
-
 .field-hint {
   display: block;
   margin-top: 0.25rem;