Add dashboard error boundaries

[thecosmicskye]

Summary

Adds reusable React error boundaries around the main dashboard layout so render failures in the header, sidebar, page content, dashboard panel, or stat-card grid do not crash the entire UI.

Changes

• Added frontend/src/components/ErrorBoundary.tsx as a reusable class-based React error boundary with a clean fallback and retry action.
• Wrapped Header, Sidebar, and main page content in distinct layout-level error boundaries.
• Refactored the Dashboard stat cards into a typed StatCardsGrid and wrapped the dashboard panel and stats grid in separate boundaries.
• Removed the loose any stat access in favor of typed DashboardStats keys.

Testing

• npm --prefix frontend install
  • PASS, 0 vulnerabilities.
• npm --prefix frontend run build
  • PASS, TypeScript and Vite production build completed.
• python3 build.py
  • Ran locally and committed diagnostics for 68fe2391.
  • Build summary: 10 modules, 7 passed, 3 failed.
  • Existing/unrelated local failures:
    • frailbox: existing C compile error in src/arena.c:179.
    • compliance: local machine has no Java Runtime.
    • openapi-haskell: local machine has no ghc.
  • Diagnostic files committed:
    • diagnostic/build-68fe2391.json
    • diagnostic/build-68fe2391-part001.logd through diagnostic/build-68fe2391-part008.logd
  • Diagnostic decrypt/reassemble details from build output:
    • cat diagnostic/build-68fe2391-part001.logd diagnostic/build-68fe2391-part002.logd diagnostic/build-68fe2391-part003.logd diagnostic/build-68fe2391-part004.logd diagnostic/build-68fe2391-part005.logd diagnostic/build-68fe2391-part006.logd diagnostic/build-68fe2391-part007.logd diagnostic/build-68fe2391-part008.logd > diagnostic/build-68fe2391.logd
    • encryptly unpack diagnostic/build-68fe2391.logd <outdir> --password eaa47c1b134923be76f8

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

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• I would like to request that my diagnostic build log is removed before merging