feat(pool,scheduling): 号池调度维度、配额冷却机制与管理后台重构

- 新增 scheduling_dimensions 模块，为每个 Key 计算多维调度状态(手动/冷却/熔断/成本/健康)
- 新增 quota_cooldown 模块，统一判定 Key 的有效冷却原因
- Pool 管理后台 API 扩展 Key 详情字段(调度状态/维度/配额/OAuth 信息)
- 前端 Pool 管理页面重写，支持调度状态展示、批量清理封禁 Key
- Handler 基类增加请求调度元数据采集，stream telemetry 增强
- 请求时间线组件增强，支持 attempted 候选展示
- Kiro OAuth 凭证导入解析改进
- 新增 usage 表 provider_key 索引迁移
- 补充调度维度、配额冷却、候选枚举等单元测试

Closes #197

Co-authored-by: AAEE86 <33052466+AAEE86@users.noreply.github.com>

tests/unit/test_monitoring_trace_attempted_subset.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+import asyncio
+from datetime import datetime, timezone
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+from src.api.admin.monitoring.trace import AdminGetRequestTraceAdapter
+from src.services.request.candidate import RequestCandidateService
+
+
+def _candidate(*, status: str, latency_ms: int | None = None) -> SimpleNamespace:
+    now = datetime.now(timezone.utc)
+    return SimpleNamespace(
+        id=f"cand-{status}",
+        request_id="req-1",
+        candidate_index=0,
+        retry_index=0,
+        provider_id=None,
+        endpoint_id=None,
+        key_id=None,
+        required_capabilities=None,
+        status=status,
+        skip_reason=None,
+        is_cached=False,
+        status_code=None,
+        error_type=None,
+        error_message=None,
+        latency_ms=latency_ms,
+        concurrent_requests=None,
+        extra_data=None,
+        created_at=now,
+        started_at=None,
+        finished_at=None,
+    )
+
+
+def _context() -> SimpleNamespace:
+    return SimpleNamespace(
+        db=MagicMock(),
+        add_audit_metadata=lambda **_: None,
+    )
+
+
+def test_trace_prefers_attempted_subset(monkeypatch: object) -> None:
+    candidates = [
+        _candidate(status="available"),
+        _candidate(status="unused"),
+        _candidate(status="failed", latency_ms=123),
+    ]
+    monkeypatch.setattr(
+        RequestCandidateService,
+        "get_candidates_by_request_id",
+        lambda _db, _request_id: candidates,
+    )
+
+    adapter = AdminGetRequestTraceAdapter(request_id="req-1")
+    response = asyncio.run(adapter.handle(_context()))
+
+    assert response.total_candidates == 1
+    assert len(response.candidates) == 1
+    assert response.candidates[0].status == "failed"
+    assert response.total_latency_ms == 123
+
+
+def test_trace_falls_back_to_all_when_no_attempted(monkeypatch: object) -> None:
+    candidates = [
+        _candidate(status="available"),
+        _candidate(status="unused"),
+    ]
+    monkeypatch.setattr(
+        RequestCandidateService,
+        "get_candidates_by_request_id",
+        lambda _db, _request_id: candidates,
+    )
+
+    adapter = AdminGetRequestTraceAdapter(request_id="req-1")
+    response = asyncio.run(adapter.handle(_context()))
+
+    assert response.total_candidates == 2
+    assert len(response.candidates) == 2
+    assert {c.status for c in response.candidates} == {"available", "unused"}