reliability: Implement global ErrorBoundary and centralized error reporting (fix #171)

[Ayinkx]

Summary:

• Add a global ErrorBoundary component (src/components/ErrorBoundary.tsx) that displays a user-friendly error UI with Refresh and Go Home actions.
• Add a centralized ErrorHandler (src/lib/errorHandler.ts) which reports errors to /api/monitoring and logs them locally.
• Add a useErrorHandler hook (src/hooks/useErrorHandler.ts) to standardize reporting and surface non-critical errors to users.
• Integrate reporting from the API client (src/api/client.ts) to send errors to monitoring (fire-and-forget) when requests fail.
• Wrap the top-level app with the ErrorBoundary in src/App.tsx so uncaught render errors are captured.

Notes:

• The branch was created from upstream/main as requested and changes were pushed to the fork branch Ayinkx:fix/issue-171-error-handling.
• Local type-checking revealed many pre-existing TypeScript/JSX errors outside the scope of this change; those are not introduced by this patch. CI should run full verification and surface any remaining issues.

Testing suggestions:

1. Run the app and trigger an error inside a component (throw in render) to verify the ErrorBoundary UI appears.
2. Simulate API failures using the existing query params (e.g., ?simulate_error or ?simulate_offline) and confirm ErrorHandler reports to /api/monitoring and that non-critical errors surface as alerts/toasts.
3. Review the PR diff for scope and provide guidance about integrating with the app's notification/toast system or adding route-level boundaries.

If you prefer, I can add route-level boundaries and integrate with the in-app notification system in a follow-up PR.