Add example brief and script workflows

Why: The example plugin needs a bound intent and a plugin-shipped script so the three P4 paths can be checked against a real plugin.
Evidence: TestRepoExamplePluginLoads accepts the plugin, asks 主题是什么？, and keeps the topic slot.
Impact: demo.brief starts the five-step workflow. demo.script stays unbound and needs runtime.workflowScripts.
Refs: feature/agent-harness-p4
Co-authored-by: Cursor <cursoragent@cursor.com>

plugins/example/intents/demo.json

@@ -6,5 +6,20 @@
     "description": "示例意图：命中『示例/演示』关键词（slots 声明即 HITL 该问什么；本示例无必填槽位）",
     "matcher": { "includes_any": ["示例", "演示"] },
     "slots": []
+  },
+  {
+    "id": "demo.brief",
+    "domain": "demo",
+    "version": 1,
+    "description": "写一份简报。必填槽位 topic，没写就问「主题是什么？」。",
+    "matcher": { "includes_any": ["简报"] },
+    "slots": [
+      {
+        "key": "topic",
+        "required": true,
+        "pattern": "主题[:：]\\s*(\\S+)",
+        "question": "主题是什么？"
+      }
+    ]
   }
 ]

plugins/example/plugin.json

@@ -32,6 +32,10 @@
     ],
     "commands": [
       "demo"
+    ],
+    "workflows": [
+      "demo-brief",
+      "demo-script"
     ]
   }
 }

plugins/example/workflows/demo-brief.json

@@ -0,0 +1,57 @@
+{
+  "id": "demo.brief",
+  "title": "示例简报",
+  "description": "命中 demo.brief 后：选篇幅、起草、落成工件、发一张结果卡，再请用户确认。",
+  "intentId": "demo.brief",
+  "steps": [
+    {
+      "id": "length",
+      "title": "篇幅",
+      "kind": "hitl",
+      "hitl": {
+        "question": "要多长？",
+        "kind": "choice",
+        "allowFreeInput": false,
+        "choices": [
+          {"id": "short", "label": "短", "description": "一段", "impact": "只写一段"},
+          {"id": "long", "label": "长", "description": "几段", "impact": "会写得更长"}
+        ]
+      }
+    },
+    {
+      "id": "draft",
+      "title": "起草",
+      "kind": "prompt",
+      "agent": "research",
+      "prompt": "写一份关于「{{slots.topic}}」的简报，篇幅：{{steps.length.output}}。",
+      "critic": {"criteria": "必须提到主题，并且是一段能读完的简报", "maxRetries": 1}
+    },
+    {
+      "id": "save",
+      "title": "成稿",
+      "kind": "artifact",
+      "artifact": "demo-brief.md",
+      "prompt": "{{steps.draft.output}}"
+    },
+    {
+      "id": "note",
+      "title": "收件",
+      "kind": "card",
+      "card": {"kind": "result", "title": "简报好了", "tone": "ok"}
+    },
+    {
+      "id": "confirm",
+      "title": "确认",
+      "kind": "hitl",
+      "hitl": {
+        "question": "这份简报可以用吗？",
+        "kind": "confirm",
+        "allowFreeInput": false,
+        "choices": [
+          {"id": "yes", "label": "可以用", "description": "结束", "impact": "不会再改"},
+          {"id": "no", "label": "先不用", "description": "结束", "impact": "不会再改"}
+        ]
+      }
+    }
+  ]
+}

plugins/example/workflows/demo-script.json

@@ -0,0 +1,13 @@
+{
+  "id": "demo.script",
+  "title": "示例脚本",
+  "description": "插件自带脚本。需要打开 runtime.workflowScripts。不绑定意图，用 run_workflow 启动。",
+  "steps": [
+    {
+      "id": "run",
+      "title": "跑脚本",
+      "kind": "script",
+      "script": "workflows/scripts/demo.py"
+    }
+  ]
+}

plugins/example/workflows/scripts/demo.py

@@ -0,0 +1,6 @@
+import agentwf as wf
+
+now = wf.tool("time_now", {})
+answer = wf.ask("要记下来吗？", [{"id": "yes", "label": "记下", "impact": "会写入一份备忘"}])
+wf.artifact("demo-script.md", "时间 " + now + "\n选择 " + answer)
+wf.step("run", "跑脚本", "done")