feat: 任务书 07，agents 模块与真实模型测试

src/agents 4 个文件 681 行：runSession 按角色开 Pi 子会话、发工具、核对实际加载内容，
提交参数非法 JSON、必填字段交 null、Pi 形状校验不通过都经提交回调记退回。
Pi 依赖固定 0.85.1；新增 npm run test:pi（glm-5.3 真实会话）。

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -8,14 +8,23 @@
   },
   "scripts": {
     "check": "tsc --noEmit -p tsconfig.json && depcruise src tests --config .dependency-cruiser.cjs",
-    "test": "node --test \"tests/**/*.test.ts\""
+    "test": "node --test \"tests/**/*.test.ts\"",
+    "test:pi": "node tests/agents-pi.ts"
   },
   "dependencies": {
+    "@earendil-works/pi-ai": "0.85.1",
+    "@earendil-works/pi-coding-agent": "0.85.1",
     "typebox": "1.3.7"
   },
   "devDependencies": {
     "@types/node": "22.19.19",
     "dependency-cruiser": "18.5.0",
     "typescript": "5.9.3"
+  },
+  "overrides": {
+    "@earendil-works/pi-agent-core": "0.85.1",
+    "@earendil-works/pi-ai": "0.85.1",
+    "@earendil-works/pi-tui": "0.85.1",
+    "@earendil-works/chord": "0.85.1"
   }
 }