feat: add error boundaries for feature modules

[MerlinTheWhiz]

Description

Add error boundary wrappers to all major feature modules so a crash in any one
component no longer takes down the entire app. Every feature page and standalone
component now has its own boundary with a graceful fallback UI.

• ErrorBoundary — full-page red-themed fallback with "Something went wrong",
  "Try Again", and "Go Home". Used for Lab and Campus pages.
• RouteErrorBoundary — amber/warning-themed per-section fallback with
  "Could not load {section}" and "Retry Section". Used inside BCIDashboard for
  per-tab isolation.
• Both now also export as default for import convenience.

Related Issue

Closes #71

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that changes existing behavior)
• 📚 Documentation update
• ♻️ Refactor (no functional change)
• 🧪 Tests
• 🔧 Chore / tooling

Packages Affected

• contracts/ (Soroban / Rust)
• backend/ (Node / Express)
• frontend/ (Next.js)
• docs/

How Has This Been Tested?

• Existing tests: all 59 existing ErrorBoundary + RouteErrorBoundary tests pass.
• New tests: 13 new tests covering BCIDashboard (tab crash → RouteErrorBoundary catches,
  tab switching recovers, sidebar stays functional, dev/prod mode) and NanoLearningHub
  (normal render, empty skills, section presence).
• Type check: tsc --noEmit clean on all modified files.
• Lint: next lint clean — no new warnings or errors.

Run with (from frontend/): npm test -- --no-cache --runInBand src/components/__tests__/
(if memory-constrained, use the programmatic inline config as described in the issue thread).

Checklist

• My code follows the project's coding standards
• I have run the relevant linters and type checks
• I have added or updated tests that prove my change works
• All new and existing tests pass locally
• I have updated documentation where needed
• My commits follow the Conventional Commits format
• I have noted any breaking changes below

Breaking Changes

None

Additional Notes / Screenshots

Files modified:

• frontend/src/components/ErrorBoundary.tsx — added default export
• frontend/src/components/RouteErrorBoundary.tsx — added default export
• frontend/src/app/lab/page.tsx — wrapped <VirtualScienceLab /> in <ErrorBoundary>
• frontend/src/app/campus/page.tsx — wrapped <MetaverseCampus /> in <ErrorBoundary>
• frontend/src/components/BCI/BCIDashboard.tsx — wrapped each tab's renderActiveTab()
  in <RouteErrorBoundary routeName={...}> for per-tab crash isolation
• frontend/src/components/NanoLearning/NanoLearningHub.tsx — wrapped JSX in <ErrorBoundary>

Files added:

• frontend/src/components/__tests__/BCIDashboard.test.tsx
• frontend/src/components/__tests__/NanoLearningHub.test.tsx

Screenshot