docs: precipitate Action/CRUD Lookup contract for skill authors

assets/examples/lookup-action.example.json

@@ -0,0 +1,48 @@
+{
+  "_comment": "形状参考：Action 参数引用同库另一张表时用 Lookup 下拉，勿让用户填内部编号。完整契约见 references/ACTIONS.md「跨表引用：Lookup」与 references/SCHEMA.md。",
+  "schemaVersion": 1,
+  "skill": "your-skill-slug",
+  "actions": [
+    {
+      "id": "send-with-template",
+      "label": "按模板发送（示例）",
+      "description": "演示内联 lookup：从 message_templates 选模板；-- 表示自动挑选。",
+      "placements": ["toolbar"],
+      "executionProfile": "async",
+      "interaction": "form",
+      "bind": {
+        "tables": ["leads"]
+      },
+      "entrypoint": {
+        "type": "cli",
+        "command": "engage",
+        "args": ["--template-id", "{{templateId}}", "--content", "{{content}}"]
+      },
+      "inputSchema": {
+        "type": "object",
+        "properties": {
+          "content": {
+            "type": "string",
+            "title": "正文",
+            "description": "填了就按这里发；留空则用下面的话术模板。",
+            "display_type": "textarea"
+          },
+          "templateId": {
+            "type": "number",
+            "title": "话术模板",
+            "description": "仅在正文留空时生效。选 -- = 自动挑选。",
+            "display_type": "lookup",
+            "lookup": {
+              "ref_table": "message_templates",
+              "value_column": "id",
+              "label_column": "name",
+              "extra_column": "channel",
+              "filter_column": "is_active",
+              "filter_value": 1
+            }
+          }
+        }
+      }
+    }
+  ]
+}