🐛 fix(table-designer): 去除 SQL 变更重复标记

- 移除 Monaco glyph margin 变更标记通道

- 仅保留 line decorations 左侧单一变更标记

- 补充防重复标记回归测试

Refs #324

frontend/src/components/TableDesignerSqlPreview.test.tsx

@@ -91,6 +91,7 @@ describe('TableDesignerSqlPreview', () => {
     expect(markup).toContain('data-theme="gonavi-sql-preview-light"');
     expect(markup).toContain('"readOnly":true');
     expect(markup).toContain('"lineNumbers":"on"');
+    expect(markup).not.toContain('"glyphMargin":true');
     expect(markup).toContain('ALTER TABLE');
     expect(markup).toContain('RENAME COLUMN');
 
@@ -143,6 +144,7 @@ describe('TableDesignerSqlPreview', () => {
           options: expect.objectContaining({
             className: expect.stringContaining('gonavi-sql-preview-change-line-add'),
             isWholeLine: true,
+            linesDecorationsClassName: expect.stringContaining('gonavi-sql-preview-change-marker-add'),
           }),
         }),
         expect.objectContaining({
@@ -150,12 +152,22 @@ describe('TableDesignerSqlPreview', () => {
           options: expect.objectContaining({
             className: expect.stringContaining('gonavi-sql-preview-change-line-drop'),
             isWholeLine: true,
+            linesDecorationsClassName: expect.stringContaining('gonavi-sql-preview-change-marker-drop'),
           }),
         }),
       ]),
     );
     const firstDecorationCall = mockEditor.deltaDecorations.mock.calls[0] as unknown as [unknown, unknown[]];
     expect(firstDecorationCall[1]).toHaveLength(2);
+    expect(firstDecorationCall[1]).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          options: expect.not.objectContaining({
+            glyphMarginClassName: expect.any(String),
+          }),
+        }),
+      ]),
+    );
   });
 
   it('uses the dark SQL preview theme when dark mode is enabled', () => {

frontend/src/components/TableDesignerSqlPreview.tsx

@@ -151,7 +151,6 @@ const TableDesignerSqlPreview: React.FC<TableDesignerSqlPreviewProps> = ({
           range: new monaco.Range(highlight.lineNumber, 1, highlight.lineNumber, endColumn),
           options: {
             className: getLineDecorationClassName(highlight.kind),
-            glyphMarginClassName: getLineDecorationMarkerClassName(highlight.kind),
             hoverMessage: { value: highlight.label },
             isWholeLine: true,
             linesDecorationsClassName: getLineDecorationMarkerClassName(highlight.kind),
@@ -233,7 +232,6 @@ const TableDesignerSqlPreview: React.FC<TableDesignerSqlPreviewProps> = ({
           automaticLayout: true,
           fontFamily: '"JetBrains Mono", "Cascadia Code", Consolas, monospace',
           fontSize: 13,
-          glyphMargin: true,
           lineNumbers: 'on',
           lineDecorationsWidth: 14,
           minimap: { enabled: false },