feat(profile): add round avatar with upload and cropping

- backend: user_avatar_objects binding (PG+SQLite), GC preserves avatar blobs,
  avatar service (EXIF-stripping WebP 128/512), public avatar read route
- web: avatar upload/crop on profile, round avatar in header/members/comments/author
- android: avatar upload/crop, round avatar on profile and albums header
- openspec: add-user-avatar proposal/design/specs/tasks

frontend/src/routes/(app)/albums/[id]/members/+page.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { page } from '$app/stores';
 	import { api } from '$lib/api';
+	import Avatar from '$lib/components/Avatar.svelte';
 	import Icon from '$lib/components/Icon.svelte';
 	import { auth } from '$lib/stores/auth.svelte';
 	import type { Album, AlbumMember } from '$lib/types';
@@ -101,8 +102,10 @@
 	</li>
 	{#each members as member (member.user_id)}
 		<li class="flex items-center justify-between gap-4 px-4 py-3">
-			<span class="text-text"
-				>{member.user.name} <span class="text-text-muted text-sm">({member.user.email})</span></span
+			<span class="text-text inline-flex items-center gap-2"
+				><Avatar name={member.user.name} url={member.user.avatar_url} size="size-7" />
+				{member.user.name}
+				<span class="text-text-muted text-sm">({member.user.email})</span></span
 			>
 			<div class="flex items-center gap-2">
 				{#if assignableRoles.length > 0}