fix(weread): recover book details from cached shelf fallback

[Astro-Han]

Description

Fix WeRead book detail fallback when private API auth has expired.

This PR improves the detail fallback chain in two cases:

• reuse the first parsed shelf snapshot instead of reloading /web/shelf before search fallback
• allow a safe raw-order fallback when shelfIndexes never hydrate but rendered shelf reader links still cover the cached entries

It also adds regression tests for:

• ordinary book fallback through public search
• rejecting same-title results when the visible author does not match
• raw-order fallback for cached entries when shelf indexes remain empty

Related issue:

• [Bug]: WeRead 登录后仍显示WeRead private API auth expired #610

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 🌐 New site adapter
• 📝 Documentation
• ♻️ Refactor
• 🔧 CI / build / tooling

Checklist

• I ran the checks relevant to this PR
• I updated tests or docs if needed
• I included output or screenshots when useful

Documentation (if adding/modifying an adapter)

• Added doc page under docs/adapters/ (if new adapter)
• Updated docs/adapters/index.md table (if new adapter)
• Updated sidebar in docs/.vitepress/config.mts (if new adapter)
• Updated README.md / README.zh-CN.md when command discoverability changed
• Used positional args for the command's primary subject unless a named flag is clearly better
• Normalized expected adapter failures to CliError subclasses instead of raw Error

Screenshots / Output

$ node dist/main.js weread shelf --limit 200 -f json
⚠  WeRead private API auth expired; showing cached shelf data from localStorage. Results may be stale, and detail commands may still require re-login.

$ node dist/main.js weread book 29196155 -f json
[
  {
    "title": "文明、现代化、价值投资与中国",
    "author": "李录",
    "publisher": "中信出版集团"
  }
]

[jackwener]

Merged after review. I specifically looked at the design intent here: make weread book detail resilient when the private API path is unavailable, while keeping fallback resolution conservative and safe. I validated with targeted Vitest, typecheck, and build before merge. Thanks for the contribution.