fix(monitoring): restore SQLite token statistics

[dadachann]

概述 / Overview

Fixes #2468.

• allows the existing SQLite token-statistics bucket query to use strftime through TenantUnitOfWork;
• preserves the backend msg when the token dashboard receives the HTTP client's structured { code, msg, data } error object, instead of displaying [object Object];
• adds a real SQLite scoped-session execution regression and behavioral tests for frontend error extraction/wiring;
• repairs the existing PostgreSQL capacity-test stub to accept and assert the runtime reconcile timeout now passed by master (the first CI run exposed this unrelated deterministic base regression).

This is an independent reimplementation of the focused fix discussed in #2473 because that contribution cannot be merged without its author's CLA signature.

更改前后对比截图 / Screenshots

No layout change.

Before: token monitoring returned HTTP 500 on SQLite, and the UI rendered [object Object].

After: SQLite time buckets execute through the tenant SQL guard; future structured API failures display their backend message.

Validation

• uv run pytest tests/unit_tests/persistence/test_tenant_uow.py -q --tb=short — 118 passed
• uv run pytest tests/unit_tests/api/service/test_monitoring_tenancy.py::test_token_statistics_aggregate_and_limit_groups_in_database -q --tb=short — passed
• uv run ruff check ... — passed
• uv run ruff format --check ... — passed
• pnpm test:unit — 54 passed
• pnpm lint — 0 errors (34 existing warnings)
• pnpm build — passed
• pnpm exec prettier --check ... — passed
• git diff --check — passed
• independent pre-commit review — passed with no security or logic findings

检查清单 / Checklist

• 阅读仓库贡献指引 / Read the contribution guide
• 已签署 CLA / Signed the CLA
• 已与项目维护者沟通（[Bug]: 仪表盘监控token数据失败返回[object Object] #2468）/ Communicated with the maintainer
• 已自行测试更改 / Tested the changes

项目维护者完成 / For project maintainer

• 相关 issue 已链接 / Related issue linked
• 无配置或迁移变更 / No configuration or migration changes
• 无新增依赖 / No new dependencies
• 无需文档更新 / No documentation update required

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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