[BF-024] PWA cache 策略和 service worker 更新机制

[baixiangcpp]

Issue

Closes #44

Scope

• Updates the service worker cache strategy for BF-024 only.
• Adds install-page controls for clearing Byteflow PWA CacheStorage buckets.
• Updates Trust Center / Install copy for the PWA cache behavior across all locales.
• Extends guards and smoke coverage for PWA cache buckets, offline behavior, external-request network-only behavior, and manual cache clear.

Implementation

• Split service worker caches into versioned buckets: app shell, static assets, tool chunks, manifest/icons, runtime pages, and metadata.
• Keeps non-GET, third-party, explicit network-only, API, and sensitive-query requests out of CacheStorage.
• Preserves the existing build-id SW version injection and update prompt path.
• Adds a localized install-page "Clear cached app files" control that deletes only byteflow-* caches and does not touch tool input/output storage.
• Guards manual cache clearing against in-flight runtime cache writes so cleared byteflow-* buckets do not reappear during the clear window.
• Documents the PWA cache strategy in Trust Center copy and Install page copy.

Validation

• npm run lint
  • PASS
• npm run test
  • PASS: 217 files / 1092 tests
• npm run validate
  • PASS
• npm run build
  • PASS: 1289 static pages, build:sw injected build id 14c3a03
• npm run test:e2e:smoke
  • PASS via npm run test:e2e:smoke -- --port=4177
• npm run test:e2e:pwa
  • PASS via npm run test:e2e:pwa -- --port=4178
• npm run check:sw-version
  • PASS: APP_VERSION uses __BUILD_ID__

Acceptance Criteria

• App shell 可离线加载。
• 本地工具核心 UI 可离线打开。
• 外部请求工具离线时显示明确网络提示。
• Service worker 不缓存 POST 或外部 API 响应。
• SW 版本更新可提示用户刷新。
• npm run check:sw-version 通过。
• npm run test:e2e:pwa 通过。

Cache Strategy

• App shell: byteflow-app-shell-v<build-id>.
• Static assets: byteflow-static-assets-v<build-id>.
• Tool chunks: byteflow-tool-chunks-v<build-id>.
• Manifest/icons: byteflow-manifest-icons-v<build-id>.
• Runtime pages: byteflow-runtime-pages-v<build-id>.
• Metadata: byteflow-meta-v<build-id>.
• Network-only: non-GET, third-party origins, /api/*, sensitive query strings, and explicit x-byteflow-cache-mode: network-only / x-byteflow-external-request: 1 requests.

Manual Checks

• Desktop install page cache-clear control screenshot captured.
• Mobile install page cache-clear control screenshot captured.
• PWA smoke verified local tool shell opens offline.
• PWA smoke verified external request probe is not cached.
• PWA smoke verified manual cache clear removes byteflow-* cache buckets.

Privacy Check

• 不采集工具输入
• 不采集工具输出
• 不新增未披露的外部请求
• 不持久化敏感 payload
• 不缓存 external-request responses
• 不新增 analytics payload/query/file-name collection

Screenshots / Evidence

• output/playwright/BF-024-install-cache-desktop.png
• output/playwright/BF-024-install-cache-mobile.png

[cloudflare-workers-and-pages]

Deploying byteflow with    Cloudflare Pages

Latest commit:	14c3a03
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