Add dashboard loading and empty states

[jcruz020409-crypto]

This cleans up the dashboard's first-load and empty-result moments.

What changed

• Added a pulsing event list skeleton so the table area does not feel blank while events are loading.
• Added shared empty states for waiting on events, no search matches, and Stellar connection trouble.
• Wired the filtered empty state to the existing clear-search flow.
• Added focused tests for the new states and the table accessibility path.

I also touched a few nearby dashboard imports and registry bits because they were blocking the page/tests locally while working through this issue.

Checks

• npx vitest run components/dashboard/EmptyState.test.tsx components/dashboard/EventListSkeleton.test.tsx components/dashboard/EventFeedTable.test.tsx
• npx eslint app/dashboard/DashboardClient.tsx app/layout.tsx components/dashboard/EventFeedTable.tsx components/dashboard/EmptyState.tsx components/dashboard/EventListSkeleton.tsx components/dashboard/EventDetailsModal.tsx lib/hooks/useLiveFeed.ts lib/hooks/useDashboardPrefs.ts lib/translator/registry.ts components/dashboard/EmptyState.test.tsx components/dashboard/EventListSkeleton.test.tsx components/dashboard/EventFeedTable.test.tsx
• Manual dashboard check in the browser

Note: the full repo lint/test/build still runs into unrelated existing blockers in the broader app, so I kept validation focused on the dashboard path touched here.

Closes #228

[Osuochasam]

@jcruz020409-crypto please resolve conflicts