chore(backlog): 记录 g135 完成

.ua/backlog.json

@@ -1443,7 +1443,7 @@
       "motivation": "字段多的编辑页只能一列往下堆，长表单要滚很久；页面里已有 grid，form 却没用上，调用方只能自己拆成多个 form（校验被割裂）",
       "acceptance": "form 新增 columns（1/2/3），>1 时字段走 grid 铺列、窄屏自动单列、按钮区始终整行；单向依赖（form 复用 grid）；manifest props/steps 与 demo 同步；npm run check 全绿",
       "notes": "自补：既有组件可用性细节",
-      "status": "open"
+      "status": "done"
     }
   ]
 }

.ua/iterations.log

@@ -179,3 +179,4 @@
 {"ts":"2026-10-26T15:22:59+08:00","id":"g132","result":"done","commit":"9d0c195","summary":"新增 mentions（@ 触发弹层、名字/关键词过滤、↑↓ 环形移动、Enter/Tab 选中、Esc 只收本层、按光标替换写回信号），组件 63→64"}
 {"ts":"2026-10-26T15:24:26+08:00","id":"g133","result":"done","commit":"0f6331c","summary":"新增 treeSelect（复用 tree 的搜索/多选/级联，单选即收起、多选保持展开，共享 Esc 栈 + 点外收起），组件 64→65"}
 {"ts":"2026-10-26T15:25:53+08:00","id":"g134","result":"done","commit":"2a9193c","summary":"新增 ua sync-counts 幂等改写三处组件计数，verify 正则覆盖 README 标题「共 N 个」并给修法提示"}
+{"ts":"2026-10-26T15:27:19+08:00","id":"g135","result":"done","commit":"21950d9","summary":"form 新增 columns（1/2/3）复用 grid 铺列，窄屏自动单列、按钮区整行；demo 注册表单改两列"}