feat: Implement note positioning logic and tests for position conversion

lib/screens/note_editor_screen.dart

@@ -336,7 +336,9 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
 
   Widget _buildCategorySelectorBox({Category? category}) {
     final String label = category?.name ?? 'Sin categoría';
-    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);
+    final IconData icon = CategoryStyle.iconForCodePoint(
+      category?.iconCodePoint,
+    );
     final Color backgroundColor = _categoryBackgroundColor(category);
     final Color foregroundColor = _categoryForegroundColor(category);
 
@@ -475,7 +477,9 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
   }) {
     final Color backgroundColor = _categoryBackgroundColor(category);
     final Color foregroundColor = _categoryForegroundColor(category);
-    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);
+    final IconData icon = CategoryStyle.iconForCodePoint(
+      category?.iconCodePoint,
+    );
 
     return InkWell(
       onTap: onTap,
@@ -510,8 +514,7 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
                 ),
               ),
             ),
-            if (isSelected)
-              Icon(Icons.check, color: foregroundColor, size: 18),
+            if (isSelected) Icon(Icons.check, color: foregroundColor, size: 18),
           ],
         ),
       ),
@@ -565,6 +568,13 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
                   crossAxisAlignment: CrossAxisAlignment.start,
                   mainAxisSize: MainAxisSize.min,
                   children: [
+                    Text(
+                      'Posicion: ${_currentNote.position}',
+                      style: const TextStyle(
+                        color: Colors.white54,
+                        fontSize: 12,
+                      ),
+                    ),
                     Text(
                       'Creado: ${_formatDate(_currentNote.createdAt)}',
                       style: const TextStyle(