Feature: Add drag-and-drop reordering for checklist items

Users can now reorder checklist items by dragging them up or down using the
drag handle icon (6-dot pattern) on each item.

Changes:
- Added ic_drag_handle.xml drawable with 6-dot pattern icon
- Updated item_checklist_row.xml to include drag handle ImageButton
- Modified ChecklistAdapter to support moveItem() operation
- Added ItemTouchHelper in NoteEditorFragment for drag-and-drop functionality
- Items reorder smoothly and changes are auto-saved

app/src/main/java/com/notesapp/adapters/ChecklistAdapter.java

@@ -23,6 +23,7 @@ public class ChecklistAdapter extends RecyclerView.Adapter<ChecklistAdapter.Chec
         void onTextChange(ChecklistItem item, String text);
         void onCheckedChange(ChecklistItem item, boolean checked);
         void onDeleteClick(int position, ChecklistItem item);
+        void onMoveItems(int fromPosition, int toPosition);
     }
 
     public ChecklistAdapter(OnItemChangeListener listener) {
@@ -88,13 +89,34 @@ public class ChecklistAdapter extends RecyclerView.Adapter<ChecklistAdapter.Chec
         return items;
     }
 
+    // Move item from one position to another
+    public void moveItem(int fromPosition, int toPosition) {
+        if (fromPosition < toPosition) {
+            for (int i = fromPosition; i < toPosition; i++) {
+                ChecklistItem temp = items.get(i);
+                items.set(i, items.get(i + 1));
+                items.set(i + 1, temp);
+            }
+        } else {
+            for (int i = fromPosition; i > toPosition; i--) {
+                ChecklistItem temp = items.get(i);
+                items.set(i, items.get(i - 1));
+                items.set(i - 1, temp);
+            }
+        }
+        
+        notifyItemMoved(fromPosition, toPosition);
+    }
+
     static class ChecklistViewHolder extends RecyclerView.ViewHolder {
+        ImageButton dragHandle;
         CheckBox checkBox;
         EditText editText;
         ImageButton deleteButton;
 
         public ChecklistViewHolder(@NonNull View itemView) {
             super(itemView);
+            dragHandle = itemView.findViewById(R.id.drag_handle);
             checkBox = itemView.findViewById(R.id.check_box);
             editText = itemView.findViewById(R.id.item_text);
             deleteButton = itemView.findViewById(R.id.delete_button);

app/src/main/java/com/notesapp/fragments/NoteEditorFragment.java

@@ -14,6 +14,7 @@ import android.widget.Toast;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -175,12 +176,39 @@ public class NoteEditorFragment extends Fragment {
                 updateProgress();
                 saveNoteImmediately();
             }
+
+            @Override
+            public void onMoveItems(int fromPosition, int toPosition) {
+                scheduleSave();
+            }
         });
         
         checklistAdapter.setItems(note.getItems());
         checklistRecyclerView.setLayoutManager(new LinearLayoutManager(requireContext()));
         checklistRecyclerView.setAdapter(checklistAdapter);
 
+        // Add drag-and-drop support
+        ItemTouchHelper itemTouchHelper = new ItemTouchHelper(
+            new ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP | ItemTouchHelper.DOWN, 0) {
+                @Override
+                public boolean onMove(@NonNull RecyclerView recyclerView, 
+                                     @NonNull RecyclerView.ViewHolder viewHolder, 
+                                     @NonNull RecyclerView.ViewHolder target) {
+                    int fromPosition = viewHolder.getAdapterPosition();
+                    int toPosition = target.getAdapterPosition();
+                    
+                    checklistAdapter.moveItem(fromPosition, toPosition);
+                    scheduleSave();
+                    
+                    return true;
+                }
+
+                @Override
+                public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {}
+            });
+        
+        itemTouchHelper.attachToRecyclerView(checklistRecyclerView);
+
         addImageButton.setOnClickListener(v -> {
             ChecklistItem newItem = new ChecklistItem("");
             note.getItems().add(newItem);

app/src/main/res/drawable/ic_drag_handle.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    
+    <!-- Top row of dots -->
+    <path
+        android:pathData="M9,3C10.105,3 11,3.895 11,5C11,6.105 10.105,7 9,7C7.895,7 7,6.105 7,5C7,3.895 7.895,3 9,3Z"
+        android:fillColor="@android:color/darker_gray"/>
+    <path
+        android:pathData="M15,3C16.105,3 17,3.895 17,5C17,6.105 16.105,7 15,7C13.895,7 13,6.105 13,5C13,3.895 13.895,3 15,3Z"
+        android:fillColor="@android:color/darker_gray"/>
+    
+    <!-- Middle row of dots -->
+    <path
+        android:pathData="M9,12C10.105,12 11,12.895 11,14C11,15.105 10.105,16 9,16C7.895,16 7,15.105 7,14C7,12.895 7.895,12 9,12Z"
+        android:fillColor="@android:color/darker_gray"/>
+    <path
+        android:pathData="M15,12C16.105,12 17,12.895 17,14C17,15.105 16.105,16 15,16C13.895,16 13,15.105 13,14C13,12.895 13.895,12 15,12Z"
+        android:fillColor="@android:color/darker_gray"/>
+    
+    <!-- Bottom row of dots -->
+    <path
+        android:pathData="M9,21C10.105,21 11,21.895 11,23C11,24.105 10.105,25 9,25C7.895,25 7,24.105 7,23C7,21.895 7.895,21 9,21Z"
+        android:fillColor="@android:color/darker_gray"/>
+    <path
+        android:pathData="M15,21C16.105,21 17,21.895 17,23C17,24.105 16.105,25 15,25C13.895,25 13,24.105 13,23C13,21.895 13.895,21 15,21Z"
+        android:fillColor="@android:color/darker_gray"/>
+
+</vector>

app/src/main/res/layout/item_checklist_row.xml

@@ -1,16 +1,27 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/item_container"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:orientation="horizontal"
     android:paddingVertical="4dp">
 
+    <ImageButton
+        android:id="@+id/drag_handle"
+        android:layout_width="32dp"
+        android:layout_height="32dp"
+        android:layout_gravity="center_vertical"
+        android:background="?attr/selectableItemBackgroundBorderless"
+        android:src="@drawable/ic_drag_handle"
+        app:tint="@color/text_secondary" />
+
     <CheckBox
         android:id="@+id/check_box"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_gravity="center_vertical" />
+        android:layout_gravity="center_vertical"
+        android:layout_marginStart="4dp" />
 
     <EditText
         android:id="@+id/item_text"