🐛 fix(oracle): 修复DDL注释拼接缺少分号与换行

- 为 Oracle 建表 DDL 追加注释前补齐语句结束符并保留空行分隔
- 修复 COMMENT ON TABLE/COLUMN 与 CREATE TABLE 粘连导致复制后无法直接执行的问题
- 补充后端 Oracle 建表语句与前端 DDL 格式化回归测试

frontend/src/utils/ddlFormat.test.ts

@@ -19,4 +19,18 @@ describe('formatDdlForDisplay', () => {
 
     expect(formatDdlForDisplay(raw, 'duckdb')).toBe(raw);
   });
+
+  it('keeps Oracle comment statements separated from create table DDL', () => {
+    const raw = `CREATE TABLE "H2"."S_BUSI" (
+  "ID" NUMBER
+) TABLESPACE "H2DB";
+
+COMMENT ON TABLE "H2"."S_BUSI" IS '业务机构信息';
+COMMENT ON COLUMN "H2"."S_BUSI"."ID" IS '主键';`;
+
+    const formatted = formatDdlForDisplay(raw, 'oracle');
+
+    expect(formatted).toContain('TABLESPACE "H2DB";\n\nCOMMENT ON TABLE "H2"."S_BUSI"');
+    expect(formatted).toContain(`COMMENT ON COLUMN "H2"."S_BUSI"."ID" IS '主键';`);
+  });
 });