What's changed?

Fixes #4466.

Fix two display issues on the React 2.0 monitor detail page:

• Reserve a separate row for the y-axis unit below the scroll legend when a history chart has both a unit and multiple series. Keep the existing compact layout when either is absent.
• Pass the selected interface locale to chart numbers and monitor-detail date/number formatters. Update the existing chart when the language changes, without requiring a page reload. Collection timestamps, investigation-window dates, alert dates and selected-history statistics follow the selected language.

Underlying values, timestamps and investigation timezone are unchanged. The shared chart locale is optional for existing consumers. No backend, API, dependency or lockfile changes; no Angular backport or pagination changes.

Validation

• Added 11 regression cases. The initial 10-case negative control fails seven assertions on the original formatting/layout code, with three compatibility cases passing.
• Focused chart, locale, collection evidence and workbench tests: 49 passed across five files.
• Full frontend suite: 1,065 files / 8,969 tests passed (pnpm test).
• All original frontend gates passed: pnpm toolchain:check, pnpm architecture, pnpm i18n:check, pnpm format:check, pnpm lint, pnpm typecheck, pnpm build, pnpm budget, pnpm dead-code and pnpm diff:check.
• Native Windows TypeScript and production builds passed. The full isolated Linux run used LF-normalized baseline sources with upstream patch bytes preserved and a temporary 4 GB Node heap; no project verification rules were disabled.
• Production frontend connected to a real HertzBeat backend and actual process metrics: checked the unit/legend gap, Chinese-English-Chinese changes, English formatting after reload, and desktop/narrow layouts. The investigation timezone remained Asia/Shanghai.

The original reproduction screenshot is included in #4466. Local production checks confirmed the unit below the legend and English chart/date formatting after switching languages.

AI assistance

AI assisted with implementation, regression tests and automated/browser checks.

Human validation

The contributor ran this revision through their local IDEA workflow and confirmed that both fixes work. All ten source-file hashes match the validated Windows checkout and Linux verification inputs; no source changes followed that confirmation.

Risk notes

Automated cases cover all five supported chart locales and explicit Shanghai/New York timestamp formatting. Live browser checks cover Chinese and English with the existing Shanghai investigation timezone; they are not claimed as live checks for every locale/timezone combination. A pre-existing unrelated CSS highlight minifier warning remains visible in the Windows build.

Checklist

• I have read the Contributing Guide.
• I have written the necessary comment explaining the axis-unit layout invariant.
• I have added the necessary unit tests and all cases have passed.

Add or update API

Not applicable: no API changes. No repository E2E suite was added or run; real-backend production-browser verification is described above.