fix: attach orphan comments to root AST node when query has no commands (#51)

## Summary
This fix prevents showing suggestions when editor starts with a comment
<img width="732" height="277" alt="image"
src="https://github.com/user-attachments/assets/e10ed9e4-d812-42a1-8a76-f22463cfcc9a"
/>




https://github.com/user-attachments/assets/ef8ef0f6-3348-442e-be05-d8e5dc3644cb

Author: bartoval

src/parser/__tests__/comments.test.ts

@@ -1051,6 +1051,38 @@ FROM a
     });
   });
 
+  describe('comment-only queries (no commands)', () => {
+    it('attaches a single-line comment to the root query node', () => {
+      const { root } = parse('// hello', { withFormatting: true });
+
+      expect(root.commands).toHaveLength(0);
+      expect(root.formatting).toMatchObject({
+        top: [
+          {
+            type: 'comment',
+            subtype: 'single-line',
+            text: ' hello',
+          },
+        ],
+      });
+    });
+
+    it('attaches a multi-line comment to the root query node', () => {
+      const { root } = parse('/* hello */', { withFormatting: true });
+
+      expect(root.commands).toHaveLength(0);
+      expect(root.formatting).toMatchObject({
+        top: [
+          {
+            type: 'comment',
+            subtype: 'multi-line',
+            text: ' hello ',
+          },
+        ],
+      });
+    });
+  });
+
   describe('many comments', () => {
     test('can attach all possible inline comments in basic RERANK command', () => {
       const src = `

src/parser/core/decorations.ts

@@ -197,6 +197,8 @@ const attachCommentDecoration = (
       const lastCommand = commands[commands.length - 1];
       if (lastCommand) {
         attachBottomComment(lastCommand, comment.node);
+      } else {
+        attachTopComment(ast, comment.node);
       }
       return;
     }