feat: add vendor filter dropdown and sorted model listing to chat UI

- Add vendor selector dropdown to filter available models
- Introduce `selectedVendor` writable store for vendor selection
- Add `vendorNames` derived store with sorted unique vendor names
- Add `filteredModels` derived store filtered by selected vendor
- Fix model deduplication to use `vendor:name` composite key
- Sort models by vendor then name, case-insensitive
- Display vendor prefix in model option labels

web/src/lib/components/chat/Models.svelte

@@ -1,20 +1,29 @@
 <script lang="ts">
   import { onMount } from 'svelte';
   import { Select } from "$lib/components/ui/select";
-  import { modelConfig, availableModels, loadAvailableModels } from "$lib/store/model-store";
+  import { modelConfig, loadAvailableModels, selectedVendor, vendorNames, filteredModels } from "$lib/store/model-store";
 
   onMount(async () => {
     await loadAvailableModels();
   });
 </script>
 
-<div class="min-w-0">
+<div class="min-w-0 flex flex-col gap-2">
+  <Select
+    bind:value={$selectedVendor}
+    class="bg-primary-800/30 border-none hover:bg-primary-800/40 transition-colors"
+  >
+    <option value="">All Vendors</option>
+    {#each $vendorNames as vendor (vendor)}
+      <option value={vendor}>{vendor}</option>
+    {/each}
+  </Select>
   <Select
     bind:value={$modelConfig.model}
     class="bg-primary-800/30 border-none hover:bg-primary-800/40 transition-colors"
   >
     <option value="">Default Model</option>
-    {#each $availableModels as model (model.name)}
+    {#each $filteredModels as model (`${model.vendor}:${model.name}`)}
       <option value={model.name}>{model.vendor} - {model.name}</option>
     {/each}
   </Select>

web/src/lib/store/model-store.ts

@@ -1,4 +1,4 @@
-import { writable } from 'svelte/store';
+import { derived, writable } from 'svelte/store';
 import { modelsApi } from '$lib/api/models';
 import { configApi } from '$lib/api/config';
 import type { VendorModel, ModelConfig } from '$lib/interfaces/model-interface';
@@ -13,13 +13,34 @@ export const modelConfig = writable<ModelConfig>({
 });
 
 export const availableModels = writable<VendorModel[]>([]);
+export const selectedVendor = writable<string>('');
+
+// Sorted unique vendor names
+export const vendorNames = derived(availableModels, ($models) =>
+  [...new Set($models.map(m => m.vendor))].sort((a, b) =>
+    a.toLowerCase().localeCompare(b.toLowerCase())
+  )
+);
+
+// Models filtered by selected vendor
+export const filteredModels = derived(
+  [availableModels, selectedVendor],
+  ([$models, $vendor]) =>
+    $vendor ? $models.filter(m => m.vendor === $vendor) : $models
+);
 
 // Initialize available models
 export async function loadAvailableModels() {
   try {
     const models = await modelsApi.getAvailable();
     console.log('Load models:', models);
-    const uniqueModels = [...new Map(models.map(model => [model.name, model])).values()];
+    const uniqueModels = [...new Map(models.map(model => [`${model.vendor}:${model.name}`, model])).values()];
+    // Sort like CLI: vendor name (case-insensitive), then model name (case-insensitive)
+    uniqueModels.sort((a, b) => {
+      const vendorCmp = a.vendor.toLowerCase().localeCompare(b.vendor.toLowerCase());
+      if (vendorCmp !== 0) return vendorCmp;
+      return a.name.toLowerCase().localeCompare(b.name.toLowerCase());
+    });
     availableModels.set(uniqueModels);
   } catch (error) {
     console.error('Client failed to load available models:', error);