Profile pictures, display name default, coloured service names

- Upload a profile picture on web and mobile. The API square-crops it to
  512px WebP, strips metadata (phone photos carry GPS), stores it in
  Postgres and serves it with immutable caching. Avatar URLs are stored as
  paths, so they survive moving the API. Arbitrary avatar URLs are no
  longer accepted (they'd let a profile track its viewers).
- New accounts get the username as typed as their display name; existing
  accounts are backfilled, and clearing it falls back to the username.
- Service names in Settings get a brand-coloured badge and larger type.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

packages/shared/src/client.ts

@@ -46,6 +46,17 @@ export function createApiClient({ baseUrl, getToken, credentials }: ApiClientOpt
     return data as T;
   }
 
+  /** Multipart upload (the browser/React Native sets the boundary itself). */
+  async function upload<T>(path: string, form: FormData): Promise<T> {
+    const headers: Record<string, string> = {};
+    const token = getToken?.();
+    if (token) headers.Authorization = `Bearer ${token}`;
+    const res = await fetch(baseUrl + path, { method: 'POST', headers, credentials, body: form });
+    const data = await res.json().catch(() => ({}));
+    if (!res.ok) throw new ApiError(res.status, (data as { error?: string }).error ?? `Upload failed (${res.status})`);
+    return data as T;
+  }
+
   const q = encodeURIComponent;
 
   return {
@@ -60,6 +71,9 @@ export function createApiClient({ baseUrl, getToken, credentials }: ApiClientOpt
     me: () => request<MeDTO>('/me'),
     updateMe: (input: UpdateMeInput) => request<MeDTO>('/me', { method: 'PATCH', body: input }),
     deleteAccount: () => request('/me', { method: 'DELETE' }),
+    /** `form` holds one file field (any name): a File on web, `{ uri, name, type }` on React Native. */
+    uploadAvatar: (form: FormData) => upload<MeDTO>('/me/avatar', form),
+    removeAvatar: () => request<MeDTO>('/me/avatar', { method: 'DELETE' }),
     setSharing: (pause: '1h' | '8h' | 'indefinitely' | null) => request<MeDTO>('/me/sharing', { method: 'PUT', body: { pause } }),
     setFeatured: (input: SetFeaturedInput) => request('/me/featured', { method: 'PUT', body: input }),
     clearFeatured: () => request('/me/featured', { method: 'DELETE' }),