fix(web): fix models dialog provider type select and split add/scan popovers

1. Fix provider type select showing blank when editing: await
   loadRequesters() before loadProvider() to ensure options are
   populated before setting the selected value.

2. Split 'Add Model' into two separate entries: a '+ Add Model'
   button for manual add and a Radar icon button for scan. Each
   opens its own popover with only one layer of tabs (model type
   for manual, no tabs for scan since types are auto-detected).

3. Fix popover position: side='bottom' instead of 'left'.

4. Fix popover scroll: model type tabs stay fixed at top, content
   area scrolls independently when it overflows.

5. Scan mode now fetches all model types at once (no modelType
   filter), and routes each scanned model to the correct API
   based on its own type field.

web/src/app/home/components/models-dialog/ModelsDialog.tsx

@@ -295,7 +295,7 @@ export default function ModelsDialog({
 
   async function handleScanModels(
     providerUuid: string,
-    modelType: ModelType,
+    modelType?: ModelType,
   ): Promise<ScanModelsResult> {
     try {
       const resp = await httpClient.scanProviderModels(providerUuid, modelType);
@@ -319,19 +319,26 @@ export default function ModelsDialog({
     setIsSubmitting(true);
     try {
       for (const item of models) {
-        if (modelType === 'llm') {
+        const effectiveType = item.model.type || modelType;
+        if (effectiveType === 'llm') {
           await httpClient.createProviderLLMModel({
             name: item.model.name,
             provider_uuid: providerUuid,
             abilities: item.abilities,
             extra_args: {},
           } as never);
-        } else {
+        } else if (effectiveType === 'embedding') {
           await httpClient.createProviderEmbeddingModel({
             name: item.model.name,
             provider_uuid: providerUuid,
             extra_args: {},
           } as never);
+        } else {
+          await httpClient.createProviderRerankModel({
+            name: item.model.name,
+            provider_uuid: providerUuid,
+            extra_args: {},
+          } as never);
         }
       }
       setAddModelPopoverOpen(null);