refactor: improve endpoint list UI consistency

- Show delete button for all endpoints on hover for uniform UI
- Change selected state to use blue theme matching main interface:
  * Blue border (border-blue-500) for selected items
  * Light blue background (bg-blue-50/dark:bg-blue-900/20)
  * Blue indicator dot (bg-blue-500/dark:bg-blue-400)
- Switch from compact list (space-y-px) to card-based layout (space-y-2)
- Add rounded corners to each endpoint item for better visual separation

src/components/ProviderForm/EndpointSpeedTest.tsx

@@ -387,8 +387,8 @@ const EndpointSpeedTest: React.FC<EndpointSpeedTestProps> = ({
 
           {/* 端点列表 */}
           {hasEndpoints ? (
-            <div className="space-y-px overflow-hidden rounded-md border border-gray-200 dark:border-gray-700">
+            <div className="space-y-2">
-              {sortedEntries.map((entry, index) => {
+              {sortedEntries.map((entry) => {
                 const isSelected = normalizedSelected === entry.url;
                 const latency = entry.latency;
 
@@ -396,18 +396,18 @@ const EndpointSpeedTest: React.FC<EndpointSpeedTestProps> = ({
                   <div
                     key={entry.id}
                     onClick={() => handleSelect(entry.url)}
-                    className={`group flex cursor-pointer items-center justify-between px-3 py-2.5 transition ${
+                    className={`group flex cursor-pointer items-center justify-between px-3 py-2.5 rounded-lg border transition ${
                       isSelected
-                        ? "bg-gray-100 dark:bg-gray-800"
+                        ? "border-blue-500 bg-blue-50 dark:border-blue-500 dark:bg-blue-900/20"
-                        : "bg-white hover:bg-gray-50 dark:bg-gray-900 dark:hover:bg-gray-850"
+                        : "border-gray-200 bg-white hover:border-gray-300 hover:bg-gray-50 dark:border-gray-700 dark:bg-gray-900 dark:hover:border-gray-600 dark:hover:bg-gray-850"
-                    } ${index > 0 ? "border-t border-gray-100 dark:border-gray-800" : ""}`}
+                    }`}
                   >
                     <div className="flex min-w-0 flex-1 items-center gap-3">
                       {/* 选择指示器 */}
                       <div
                         className={`h-1.5 w-1.5 flex-shrink-0 rounded-full transition ${
                           isSelected
-                            ? "bg-gray-900 dark:bg-gray-100"
+                            ? "bg-blue-500 dark:bg-blue-400"
                             : "bg-gray-300 dark:bg-gray-700"
                         }`}
                       />
@@ -436,7 +436,6 @@ const EndpointSpeedTest: React.FC<EndpointSpeedTestProps> = ({
                         <div className="text-xs text-gray-400">—</div>
                       )}
 
-                      {entry.isCustom && (
                       <button
                         type="button"
                         onClick={(e) => {
@@ -447,7 +446,6 @@ const EndpointSpeedTest: React.FC<EndpointSpeedTestProps> = ({
                       >
                         <X className="h-4 w-4" />
                       </button>
-                      )}
                     </div>
                   </div>
                 );