feat: precipitate grid presentation (row/column/region) into skill contract

assets/examples/README.md

@@ -3,6 +3,7 @@
 - `version-response.json`：`python main.py version` 成功时 stdout 单行对象的形状参考。
 - `skill-policy-snapshot.*.example.json`：Data Policy Snapshot 形状参考（见 `references/POLICY.md`）。
 - `skill-cell-presentation.example.json`：数据管理单元格呈现文档形状参考（见 `references/CELL_PRESENTATION.md`）。
+- `skill-grid-presentation.example.json`：数据管理整行 / 整列 / 区域呈现文档形状参考（见 `references/CELL_PRESENTATION.md`）。
 - `render-html.action.example.json`：HTML 报告「重新生成」Action 形状参考（固定 id `render-html`；见 `references/ACTIONS.md`）。
 - `lookup-action.example.json`：Action 内联 Lookup 形状参考（单选 + `multiple: true` 多选并列；跨表引用勿填编号；见 `references/ACTIONS.md`「跨表引用：Lookup」）。
 - `visible-when-action.example.json`：Action 参数字段条件显隐 `visibleWhen` 形状参考（互斥模式联动；见 `references/ACTIONS.md`「字段条件显隐」；≠ Policy L3）。

assets/examples/skill-grid-presentation.example.json

@@ -0,0 +1,32 @@
+{
+  "schemaVersion": 1,
+  "skill": "your-skill-slug",
+  "table": "business_records",
+  "rowKey": "id",
+  "generatedAt": "2026-08-10T06:00:00Z",
+  "rules": [
+    {
+      "ruleKey": "qty-low-rows",
+      "rows": ["42", "99"],
+      "columns": "all",
+      "tone": "danger",
+      "message": "库存低于安全线",
+      "alert": true
+    },
+    {
+      "ruleKey": "status-column",
+      "rows": "all",
+      "columns": ["status"],
+      "tone": "warning",
+      "message": "待审核"
+    },
+    {
+      "ruleKey": "overdue-print-region",
+      "rows": ["7", "8"],
+      "columns": ["print_done_at", "ship_done_at"],
+      "tone": "danger",
+      "message": "环节到期未填",
+      "alert": true
+    }
+  ]
+}