feat: Introduce application version display in the frontend footer, showing both frontend and backend versions with integrated build arguments.

frontend/src/App.css

@@ -1,4 +1,7 @@
 .app-container {
+  display: flex;
+  flex-direction: column;
+  min-height: 90vh;
   width: 100%;
   max-width: 600px;
   background: var(--panel-bg);
@@ -11,6 +14,27 @@
   animation: slideIn 0.5s ease-out;
 }
 
+.main-content {
+  flex-grow: 1;
+}
+
+.app-footer {
+  margin-top: 2rem;
+  padding-top: 1rem;
+  text-align: center;
+  color: var(--text-muted);
+  font-size: 0.85em;
+  border-top: 1px solid var(--border-color);
+}
+
+.app-footer code {
+  background: rgba(139, 92, 246, 0.1);
+  padding: 0.2rem 0.4rem;
+  border-radius: 6px;
+  margin: 0 0.2rem;
+  color: var(--accent-primary);
+}
+
 @keyframes slideIn {
   from {
     opacity: 0;