fix(dashboard): show actionable error messages instead of raw API errors

[BYK]

Summary

• Add shared enrichDashboardError() helper that converts raw 404/403/400 API errors into ResolutionError instances with actionable suggestions
• Wire into all dashboard API calls across list, view, create, and widget add/edit/delete commands
• Add 9 unit tests covering each error status code mapping

Before:

Error: API request failed: 404 Not Found
  Endpoint: /organizations/my-org/dashboards/

After:

Organization 'my-org' not found or has no dashboards.

Try:
  sentry dashboard list <org>/

Or:
  - Verify the organization slug with: sentry org list
  - Check that you have access to the organization

Closes #448

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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New Features ✨

• (init) Surface server-provided detail in spinner messages by MathurAditya724 in #588
• AsyncIterable streaming support for library SDK by BYK in #586

Bug Fixes 🐛

• (auth) Skip stale cached user info for env var tokens in auth status by BYK in #589

• (dashboard) Show actionable error messages instead of raw API errors by BYK in #592

• (upgrade) Move delta patch log.info outside spinner callback by BYK in #590

Internal Changes 🔧

• Regenerate skill files and command docs by github-actions[bot] in 0276f760

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_{🤖 This preview updates automatically when you update the PR.}

[github-actions]

Codecov Results 📊

✅ 126 passed | Total: 126 | Pass Rate: 100% | Execution Time: 0ms

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	—
Failed Tests	—
Skipped Tests	—

✨ No test changes detected

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 1265 uncovered lines.
✅ Project coverage is 95.67%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
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+ Coverage    95.66%    95.67%    +0.01%
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  Files          202       202         —
  Lines        29143     29233       +90
  Branches         0         0         —
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+ Hits         27878     27968       +90
- Misses        1265      1265         —
- Partials         0         0         —

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