Worker 失败原因不再只留类名：区分"可落库的固定文案"与"异常消息"

起因是查 Worker 运行状态时发现库里 373 条死信的 last_error 全是裸的 "ValueError"
（工具 tools/probe_worker_state.py，证据 docs/evidence/worker-state.json）。
dispatch（run not found）、dispatch_run_completed、dispatch_memory_extraction、
dispatch_profile_rebuild 抛的都是 ValueError，只记类名等于把"哪一处失败"也一起丢了。

但"直接存 str(exc)"是错的：tests/unit/worker/test_outbox_worker.py 那条
RuntimeError("credential=do-not-log") 断言异常消息不得落库 —— 它可能含凭据、SQL 或
客户标识。第一版改动就是这么写的，被这个测试当场拦下（这测试写得值）。

折中：

- 新增 OutboxHandlerError（继承 ValueError，这些失败本就是 ValueError 语义，保持
  继承关系才不会改动既有的 except ValueError 行为与断言）。它的 reason 由代码写死、
  不含任何请求数据，因此可以落库；
- safe_error_text：OutboxHandlerError → "类名: 固定文案"（截断 500 字符），
  其余异常 → 仍只记类名；
- runtime.py 的 5 处 handler 失败改抛 OutboxHandlerError。

测试：新增"固定文案落库"用例；并把既有用例的断言收紧为 last_error == "RuntimeError"
（原先只断言"不含 do-not-log"，太松，漏掉的情况测不出来）。

顺带产出 tools/probe_worker_state.py（只读）：outbox / agent_run 各状态计数、按事件
类型分组、死信原因聚合。当前环境实测 pending 347、dead 373、published 410、
agent_run 无 queued/running。

门禁：ruff 干净 / mypy 138 文件 / 697 unit+contract / 33 integration。

docs/evidence/worker-state.json

@@ -0,0 +1,135 @@
+{
+  "outbox_columns": [
+    "id",
+    "event_id",
+    "event_type",
+    "aggregate_type",
+    "aggregate_id",
+    "trace_id",
+    "payload",
+    "status",
+    "retry_count",
+    "next_retry_at",
+    "last_error",
+    "occurred_at",
+    "published_at",
+    "created_at",
+    "updated_at"
+  ],
+  "agent_run_columns": [
+    "id",
+    "run_id",
+    "idempotency_id",
+    "session_id",
+    "user_id",
+    "agent_type",
+    "trace_id",
+    "request_message_id",
+    "result_message_id",
+    "status",
+    "attempt_count",
+    "worker_id",
+    "locked_until",
+    "error_code",
+    "result_version",
+    "cancel_requested_at",
+    "started_at",
+    "completed_at",
+    "created_at",
+    "updated_at"
+  ],
+  "outbox_by_status": {
+    "dead": 373,
+    "failed": 3,
+    "pending": 347,
+    "published": 410
+  },
+  "agent_run_by_status": {
+    "failed": 21,
+    "succeeded": 184
+  },
+  "outbox_created_at_range": [
+    "2026-09-09 06:55:06.787006",
+    "2026-09-11 07:21:23.195457"
+  ],
+  "outbox_total": 1133,
+  "agent_run_total": 205,
+  "outbox_by_event_type_status": [
+    {
+      "event_type": "agent.run_requested",
+      "status": "dead",
+      "count": 373
+    },
+    {
+      "event_type": "agent.run_requested",
+      "status": "pending",
+      "count": 132
+    },
+    {
+      "event_type": "agent.run_requested",
+      "status": "published",
+      "count": 130
+    },
+    {
+      "event_type": "agent.run_completed",
+      "status": "published",
+      "count": 118
+    },
+    {
+      "event_type": "memory.extraction_requested",
+      "status": "published",
+      "count": 106
+    },
+    {
+      "event_type": "profile.rebuild_requested",
+      "status": "pending",
+      "count": 76
+    },
+    {
+      "event_type": "agent.run_completed",
+      "status": "pending",
+      "count": 66
+    },
+    {
+      "event_type": "memory.extraction_requested",
+      "status": "pending",
+      "count": 60
+    },
+    {
+      "event_type": "config.cache_invalidate_requested",
+      "status": "published",
+      "count": 42
+    },
+    {
+      "event_type": "profile.rebuild_requested",
+      "status": "published",
+      "count": 13
+    },
+    {
+      "event_type": "config.cache_invalidate_requested",
+      "status": "pending",
+      "count": 13
+    },
+    {
+      "event_type": "agent.run_requested",
+      "status": "failed",
+      "count": 3
+    },
+    {
+      "event_type": "memory.invalidated",
+      "status": "published",
+      "count": 1
+    }
+  ],
+  "dead_last_errors": [
+    {
+      "last_error": "ValueError",
+      "count": 372
+    },
+    {
+      "last_error": "no handler registered",
+      "count": 1
+    }
+  ],
+  "episode_probe_error": "ImportError: cannot import name 'MemoryEpisode' from 'app.model.memory' (C:\\Users\\Windows\\Desktop\\项目代码\\app\\model\\memory.py)"
+}