feat(agent): 运行时从 pi-agent-core 0.99.2 迁到 pi-durable 1.1.0 + pi-ai 1.1.0

- PiAgentRuntime 改用 pi-durable Harness:每个 run 一个 JSONL 存储目录 sessionDir/<runId>/ + root 对话;
  系统提示 / 能力工具 / 白名单与预算钩子装在每次运行自己的扩展里;watchEvents 翻译成 AgentRunEvent
- 挂起(工具内 close)立即封口,调用保持未完成,重开后 resume 重放;replayGate 用调用级 memo
- 旧格式 <runId>.jsonl 打开时抛 LegacySessionError;skills 加载与 <skill> 块格式内置(源自 pi-agent-core,MIT)
- tool_call_end 新增可选 durationMs;用量取 pi.usage 合计(整段会话总量)
- Azure provider 改名 azure,迁移 0093 改存量;移除 pi-agent-core,锁 pi-durable/pi-ai/chord 1.1.0
- 文档:ADR-003、pi-providers、runbook、agent README、CHANGELOG

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

packages/agent/test/settings.test.ts

@@ -38,7 +38,12 @@ describe("AgentSettings → pi-ai", () => {
     });
     const { model } = resolveModelFromSettings(s);
     expect(model).toMatchObject({ api: "openai-completions", baseUrl: "http://llm.local/v1", reasoning: false });
-    expect(compactionFromSettings(s, 32_000)).toEqual({ enabled: true, reserveTokens: 8000, keepRecentTokens: 8000 });
+    expect(compactionFromSettings(s, 32_000)).toEqual({
+      enabled: true,
+      reserveTokens: 8000,
+      keepRecentTokens: 8000,
+      backgroundTokens: 0,
+    });
     const manual = resolveAgentSettings({ ...s, compaction: { mode: "manual", threshold: 0.8 } });
     expect(compactionFromSettings(manual, 32_000).enabled).toBe(false);
     expect(() => resolveAgentSettings({ ...base, model: "" })).toThrow();