chore: add copyright headers to web dashboard components

[karagozemin]

Add a per-file copyright header so ownership is visible at the file level (consistent with the root LICENSE).

Mechanical change — prepend this exact line as the first line of each file, nothing else:

// Copyright (c) 2026 Sub Rosa contributors

Add it to the following files:

• apps/web/src/components/dashboard/DashboardEmptyState.tsx
• apps/web/src/components/dashboard/DashboardErrorState.tsx
• apps/web/src/components/dashboard/KeeperStatusCard.tsx
• apps/web/src/components/dashboard/RoundStatusCard.tsx
• apps/web/src/components/dashboard/SettlementCard.tsx
• apps/web/src/components/dashboard/index.ts

[Santia2004]

Hi team! I’d love to work on this issue. I have solid experience with the tech stack, understand the requirements, and can deliver a clean implementation with full test coverage following your project guidelines. Could you please assign this to me? Thanks!