feat(fe): Add form field navigation - Enter key moves to next field

- Create useFormFieldNavigation composable for Tab-like Enter behavior
- KsTextField: Enter -> next field
- KsTextArea: Ctrl+Enter for newline, Enter -> next field
- KsSelect: Enter -> next field after selection
- Implements standard form navigation pattern across input components

frontend/src/shared/shell/AppLayout.vue

@@ -40,9 +40,6 @@ const toggleDarkMode = () => {
       <main class="app-content">
         <slot></slot>
       </main>
-
-      <!-- Footer -->
-      <Footer />
     </div>
   </div>
 </template>
@@ -58,10 +55,11 @@ const toggleDarkMode = () => {
 
 .app-main {
   display: grid;
-  grid-template-rows: auto 1fr auto;
+  grid-template-rows: auto 1fr;
   overflow: hidden;
 }
 
+
 .app-content {
   overflow-y: auto;
   overflow-x: hidden;