Hide Local (Whisper) mode option when using cloud-only sidecar

- Expose is_cloud_only flag in /api/status response
- Add isCloudOnly to backend store state
- Conditionally hide Local (Whisper) radio button in Settings

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/components/Settings.svelte

@@ -453,6 +453,7 @@
             />
             Managed Service
           </label>
+          {#if !backendStore.isCloudOnly}
           <label>
             <input
               type="radio"
@@ -462,6 +463,7 @@
             />
             Local (Whisper)
           </label>
+          {/if}
         </div>
         {#if remoteMode === "byok"}
           <div class="field">

src/lib/stores/backend.svelte.ts

@@ -19,6 +19,7 @@ interface BackendState {
   wsConnection: WebSocket | null;
   version: string;
   lastError: string;
+  isCloudOnly: boolean;
 }
 
 let state = $state<BackendState>({
@@ -30,6 +31,7 @@ let state = $state<BackendState>({
   wsConnection: null,
   version: "1.4.0",
   lastError: "",
+  isCloudOnly: false,
 });
 
 let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
@@ -72,6 +74,9 @@ async function pollStatus() {
       if (data.version) {
         state.version = data.version;
       }
+      if (data.is_cloud_only !== undefined) {
+        state.isCloudOnly = data.is_cloud_only;
+      }
     }
   } catch {
     // API not ready yet, will retry
@@ -285,6 +290,9 @@ export const backendStore = {
   get lastError() {
     return state.lastError;
   },
+  get isCloudOnly() {
+    return state.isCloudOnly;
+  },
   get apiBaseUrl() {
     return `http://localhost:${state.port}`;
   },