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/App.vue

@@ -4,21 +4,29 @@ import { useAuthStore } from './stores/auth';
 import { useThemeStore } from './stores/theme';
 import { useLocaleStore } from './stores/locale';
 import { useUiStore } from './stores/ui';
+import { fileUrl } from './files';
 import SettingsWindow from './components/SettingsWindow.vue';
 import TimeTrackerButton from './components/TimeTrackerButton.vue';
+import Bell from './components/Bell.vue';
 
 const auth = useAuthStore();
 const theme = useThemeStore();
 const locale = useLocaleStore();
 const ui = useUiStore();
 
+const bgRaw = computed(() => auth.user?.bgImage || '');
+const bgIsImage = computed(() => /^(https?:\/\/|\/uploads|data:)/.test(bgRaw.value));
 const bgStyle = computed(() => {
-  const bg = auth.user?.bgImage || '';
-  if (!bg) return {};
-  const style = { backgroundImage: bg.startsWith('http') ? `url("${bg}")` : bg };
-  if (auth.user?.bgBlur !== false) style.filter = 'blur(14px) brightness(0.85)';
+  if (!bgRaw.value) return {};
+  const style = {
+    backgroundImage: bgIsImage.value ? `url("${fileUrl(bgRaw.value)}")` : bgRaw.value,
+    backgroundSize: 'cover',
+    backgroundPosition: 'center',
+  };
+  if (auth.user?.bgBlur !== false) style.filter = 'blur(16px) brightness(0.9)';
   return style;
 });
+const glassOn = computed(() => !!bgRaw.value && auth.user?.bgGlass !== false);
 
 onMounted(() => {
   locale.set(locale.locale);
@@ -28,9 +36,10 @@ onMounted(() => {
 </script>
 
 <template>
-  <div>
-    <div v-if="bgStyle.backgroundImage" class="bg-layer" :style="bgStyle"></div>
+  <div :class="{ 'has-bg': !!bgRaw, glass: glassOn }">
+    <div v-if="bgRaw" class="bg-layer" :style="bgStyle"></div>
     <div v-if="auth.isLoggedIn" class="top-right">
+      <Bell />
       <TimeTrackerButton />
       <button class="ghost icon-btn" @click="ui.openSettings()" title="⚙️">⚙️</button>
     </div>