feat(ui): replace emoji icons with fontawesome icons

Add Font Awesome dependency and replace all emoji icons with corresponding Font Awesome icons across components. This provides better visual consistency and scalability.

src/views/Sessions.vue

@@ -6,7 +6,7 @@
         <div class="sessions-grid">
             <div v-for="session in sessions" :key="session.ID" class="session-card">
                 <div class="card-header">
-                    <div class="session-icon">🔑</div>
+                    <div class="session-icon"><i class="fas fa-key" aria-hidden="true"></i></div>
                     <div class="session-info">
                         <div class="session-user">{{ session.username }}</div>
                         <div class="session-id">{{ session.ID }}</div>