Add Blossom admin UI for viewing all users' storage (v0.36.21)

- Add ListAllUserStats() storage method to aggregate user blob stats
- Add handleAdminListUsers() handler for admin endpoint
- Add /blossom/admin/users route requiring admin ACL
- Add Admin button to Blossom UI for admin/owner roles
- Add admin view showing all users with file counts and sizes
- Add user detail view to browse individual user's files
- Fetch user profiles (avatar, name) for admin list display

Files modified:
- pkg/blossom/storage.go: Add UserBlobStats struct and ListAllUserStats()
- pkg/blossom/handlers.go: Add handleAdminListUsers() handler
- pkg/blossom/server.go: Add admin/users route
- app/web/src/BlossomView.svelte: Add admin view state, UI, and styles

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/version/version

@@ -1 +1 @@
-v0.36.20
+v0.36.21