Add sloth emoji to section labels, friendlier network error

- Add sloth emoji prefix to "Downloaded" and "Recommended" section
  labels in the Hub model picker so they are visually distinct.
- Replace browser network errors ("NetworkError when attempting to
  fetch resource" / "Failed to fetch") with a clearer message:
  "Studio isn't running -- please relaunch it."

studio/frontend/src/components/assistant-ui/model-selector/pickers.tsx

@@ -495,7 +495,7 @@ export function HubModelPicker({
         <div className="p-1">
           {!showHfSection && (cachedGguf.length > 0 || cachedModels.length > 0) ? (
             <>
-              <ListLabel>Downloaded</ListLabel>
+              <ListLabel>{"\uD83E\uDDA5"} Downloaded</ListLabel>
               {cachedGguf.map((c) => (
                 <div key={c.repo_id}>
                   <ModelRow
@@ -525,7 +525,7 @@ export function HubModelPicker({
 
           {!showHfSection ? (
             <>
-              <ListLabel>Recommended</ListLabel>
+              <ListLabel>{"\uD83E\uDDA5"} Recommended</ListLabel>
               {recommendedIds.length === 0 ? (
                 <div className="px-2.5 py-2 text-xs text-muted-foreground">
                   No default models.

studio/frontend/src/features/auth/api.ts

@@ -84,7 +84,15 @@ export async function authFetch(
     headers.set("Authorization", `Bearer ${accessToken}`);
   }
 
-  const response = await fetch(input, { ...init, headers });
+  let response: Response;
+  try {
+    response = await fetch(input, { ...init, headers });
+  } catch (err) {
+    if (err instanceof TypeError) {
+      throw new Error("Studio isn't running -- please relaunch it.");
+    }
+    throw err;
+  }
   if (await isPasswordChangeRequiredResponse(response)) {
     void redirectToAuth();
     return response;