feat(frontend): bell, chat, uploads, glass, teams UI, fixes

- Notification bell with invites (accept/decline refreshes workspaces)
  and unread badge (polling + socket push); team chat view realtime
- Avatar/background uploads in settings + glassmorphism widgets toggle;
  background layer resolves /uploads URLs; full-bleed blurred backdrop
- Sidebar: visible creation errors, working sub-pages (parent_id),
  TEAM badge workspaces, refresh button, chat nav; admin creates users
- Tasks: per-team boards, assignee select with avatars; admin tabs for
  users/teams/groups (team workspaces, permission checkboxes)
- Register view removed (admin-only accounts); login localized;
  prettier emoji set; scaling/overflow + mobile fixes

frontend/src/components/InviteModal.vue

@@ -25,7 +25,7 @@ async function invite() {
   if (!target) return;
   try {
     await api.post(`/workspaces/${props.workspaceId}/members`, { email: target, role: role.value });
-    msg.value = `🎉 ${target} → ${role.value}`;
+    msg.value = `✨ ${target} → ${role.value}`;
     email.value = '';
     picked.value = null;
     emit('invited');