feat(frontend): chat tabs, flat SVG icons, upload autosave, per-user rights

- Chat rework: Chats (private DMs with user search, online dots, unread
  badges) and Team chats tabs; shared message component with reactions,
  edit, image attachments, message search and typing indicators
- Flat modern inline SVG icon set (no external dependency) replaces
  emoji chrome across nav, headers, buttons, tabs and settings
- Uploaded avatar/background images apply instantly (auto-save) with
  confirmation note; per-user permission matrix in dashboard members
- Login localized, invite header uses icon, comment header cleaned

frontend/src/views/Calendar.vue

@@ -5,6 +5,7 @@ import api from '../api';
 import { useWorkspaceStore } from '../stores/workspace';
 import { useLocaleStore } from '../stores/locale';
 import Sidebar from '../components/Sidebar.vue';
+import Icon from '../components/Icon.vue';
 
 const ws = useWorkspaceStore();
 const L = useLocaleStore();
@@ -77,7 +78,7 @@ onMounted(async () => {
     <Sidebar />
     <main class="main">
       <div class="topbar">
-        <h2 style="margin: 0">🗓️ {{ L.t('cal.title') }} — {{ monthName }}</h2>
+        <h2 style="margin: 0"><Icon name="calendar" :size="22" /> {{ L.t('cal.title') }} — {{ monthName }}</h2>
         <div class="row">
           <button class="ghost" @click="prev">◀</button>
           <button class="ghost" @click="goToday">{{ L.t('cal.today') }}</button>
@@ -95,12 +96,12 @@ onMounted(async () => {
               :title="t.title"
               @click="router.push('/tasks')"
             >
-              {{ t.status === 'done' ? '✅' : '📌' }} {{ t.title }}
+              {{ t.status === 'done' ? '✅' : '▸' }} {{ t.title }}
             </div>
           </template>
         </div>
       </div>
-      <p class="muted">📌 {{ L.t('task.due') }} → {{ L.t('cal.title') }} ✨</p>
+      <p class="muted">▸ {{ L.t('task.due') }} → {{ L.t('cal.title') }} ✨</p>
     </main>
   </div>
 </template>