Add error boundary components to key routes

[vayungodara]

Problem

No React error boundaries are visible in the codebase. If a component throws, the entire app white-screens with no recovery path.

What to change

• Create a reusable ErrorBoundary component in components/
• Wrap key route layouts (dashboard, pacts, groups) with error boundaries
• Show a user-friendly fallback UI with a retry button
• Log errors to console (or a future error tracking service)

Acceptance criteria

• ErrorBoundary component created and exported
• Key route layouts wrapped
• Fallback UI shows a helpful message and retry option
• Component errors no longer white-screen the app

Label: bug | Priority: high

[vayungodara]

Already implemented: components/ErrorBoundary.js exists and wraps all dashboard routes in DashboardLayout.js.