fix: public-mode profile shows letter X — GQL query referenced authed-only field

Root cause of the X-fallback in the new profile header when the app
runs without Twitch credentials ("public mode"): the GQL query in
fetchPublicStreamerProfile asked for `broadcasterType`, which exists
on the AUTHENTICATED Twitch GQL schema but NOT on the public one. The
public endpoint returned `errors[]` with "Cannot query field
broadcasterType on type User", which fetchPublicTwitchGql correctly
treats as a complete failure and returns null. That cascaded:
- avatarUrl stayed empty
- displayName fell back to the lowercase login
- description stayed empty
- partner/affiliate badge never rendered
- the renderer hit the letter-tile fallback path

Reproduced live against gql.twitch.tv with a curl-equivalent: the
exact query worked when broadcasterType was swapped for the public-
schema field roles{isPartner isAffiliate}. xrohat correctly comes
back as Partner, with the full 150x150 avatar URL, real displayName
"xRohat", and 1.25M follower count.

The 4.6.18 data-URL fetch fix is still right (Electron renderer img
loading against the Twitch CDN was its own minor headache) — it just
never got exercised because we never had a URL to fetch in the first
place. With this fix the data-URL path now activates on every
public-mode profile load, and avatars actually render.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main.ts

@@ -2393,7 +2393,7 @@ interface PublicProfileQueryResult {
         displayName: string;
         description: string | null;
         profileImageURL: string | null;
-        broadcasterType: string | null;
+        roles?: { isPartner: boolean; isAffiliate: boolean } | null;
         followers?: { totalCount: number } | null;
     } | null;
 }
@@ -2405,6 +2405,13 @@ async function fetchPublicStreamerProfile(login: string): Promise<{
     broadcasterType: '' | 'partner' | 'affiliate';
     followerCount: number | null;
 } | null> {
+    // The public (unauthenticated) GQL schema does NOT expose
+    // `broadcasterType` directly — querying it returns an errors[] response
+    // which the upstream helper treats as a complete failure (null data),
+    // which in turn left the avatar empty and the user's whole profile
+    // fell through to the fallback letter tile. Use `roles{isPartner
+    // isAffiliate}` instead, which the public schema does expose, and
+    // derive broadcasterType locally.
     const data = await fetchPublicTwitchGql<PublicProfileQueryResult>(
         `query($login: String!) {
             user(login: $login) {
@@ -2413,19 +2420,22 @@ async function fetchPublicStreamerProfile(login: string): Promise<{
                 displayName
                 description
                 profileImageURL(width: 150)
-                broadcasterType
+                roles { isPartner isAffiliate }
                 followers { totalCount }
             }
         }`,
         { login }
     );
     if (!data?.user) return null;
-    const bt = (data.user.broadcasterType || '').toLowerCase();
+    const roles = data.user.roles;
+    const broadcasterType: '' | 'partner' | 'affiliate' = roles?.isPartner
+        ? 'partner'
+        : (roles?.isAffiliate ? 'affiliate' : '');
     return {
         displayName: data.user.displayName || login,
         avatarUrl: data.user.profileImageURL || '',
         description: data.user.description || '',
-        broadcasterType: (bt === 'partner' || bt === 'affiliate') ? bt : '',
+        broadcasterType,
         followerCount: typeof data.user.followers?.totalCount === 'number' ? data.user.followers.totalCount : null
     };
 }