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/ui/components/KsTextArea.vue

@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import { computed, ref } from 'vue'
+import { useFormFieldNavigation } from '../composables/useFormFieldNavigation'
 
 export interface KsTextAreaProps {
   modelValue: string
@@ -36,6 +37,7 @@ const emit = defineEmits<{
 
 const isFocused = ref(false)
 const id = computed(() => props.inputId || `textarea-${Math.random().toString(36).substr(2, 9)}`)
+const { inputRef, handleKeyDown } = useFormFieldNavigation()
 
 const containerClass = computed(() => [
   'ks-textarea',
@@ -65,6 +67,10 @@ const handleInput = (event: Event) => {
   emit('update:modelValue', target.value)
   emit('input', event)
 }
+
+const handleKeyPress = (event: KeyboardEvent) => {
+  handleKeyDown(event, true)
+}
 </script>
 
 <template>
@@ -78,6 +84,7 @@ const handleInput = (event: Event) => {
     <!-- Textarea container -->
     <div class="ks-textarea__container">
       <textarea
+        ref="inputRef"
         :id="id"
         :value="modelValue"
         :placeholder="placeholder"
@@ -93,6 +100,7 @@ const handleInput = (event: Event) => {
         @input="handleInput"
         @focus="handleFocus"
         @blur="handleBlur"
+        @keydown="handleKeyPress"
       />
     </div>