refactor: extract provider logic into modular registry

Each AI provider now has its own module implementing a ProviderModule
interface with createGateway, getAuthHeaders, and fetchModels methods.
This replaces the monolithic switch statements in ai-provider.ts and
models.post.ts with a clean registry pattern.

app/components/Settings/AIServiceProvider.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { sortByReleaseDate } from '~/utils/sort';
 import { encryptData, decrypt, uint8ArrayToBase64, base64ToUint8Array } from '~/utils/crypto';
-import { providerBaseUrls, Providers, type Model } from '~/types/model';
+import { type Model } from '~/types/model';
 import ModelItem from './ModelItem.vue';
 import RowVirtualizerDynamic from '../RowVirtualizerDynamic.vue';
 
@@ -31,10 +31,10 @@ const modelSearch = ref('');
 
 watch(() => props.params, () => {
     if (props.params === undefined) return;
-    console.log(scrollContainerRef.value);
     apiKey.value = provider.value?.config.apiKey ?? '';
     apiProxyUrl.value = provider.value?.config.apiProxyUrl ?? '';
     modelSearch.value = '';
+    apiKeyVisible.value = false;
 
     nextTick(() => {
         if (scrollContainerRef.value) {
@@ -339,7 +339,7 @@ const saveCustomModel = async () => {
     if (editingModel.value) {
         await updateModel(editingModel.value!.id, { ...previewModelWithoutId });
     } else {
-        await createModel(previewModelWithoutId);
+        await createModel(previewModelWithoutId as Model);
     }
 
     showAddModelPanel.value = false;
@@ -403,7 +403,7 @@ defineEmits(['navigate']);
         <div class="flex flex-row justify-between gap-16">
             <label class="whitespace-nowrap" for="provider-api-key">API Proxy URL</label>
             <div class="text-sm font-mono flex flex-row rounded-md bg-[var(--bg-container)] items-center gap-1 w-7/10">
-                <input :placeholder="provider.type ? providerBaseUrls[provider.type as typeof Providers[number]] : ''"
+                <input :placeholder="provider.defaultBaseUrl || ''"
                     class="placeholder:text-[var(--text-tertiary)] w-full px-2 py-1 bg-transparent" type="text"
                     id="provider-proxy-url" :value="apiProxyUrl"
                     @input="updateProxyUrl(($event.target! as HTMLInputElement).value)" />