fix(dashboard): remove merge/duplication artifacts in App and EventEx…

[MAN7A-afk]

Fixes corrupted dashboard files caused by a bad merge. The following files each had duplicate/interleaved component definitions from multiple concatenated versions, causing TypeScript/JSX parse errors that cascaded across the build:

• App.tsx — contained ~5 different App component versions merged together, with duplicate export function App() blocks and incompatible imports
• EventExplorerCard.tsx — duplicate EventExplorerCardProps interfaces and two interleaved function signatures
• EventExplorerTable.tsx — same pattern: duplicate interface and function definitions merged together
• EventExplorerPage.tsx — two conflicting <EventExplorerTable> usages with incompatible props interleaved in the render logic

Each file was restored to a single clean implementation, preserving existing behavior (tab URL sync in App.tsx, table/card props in EventExplorer components). Verified via static diagnostics — no remaining syntax or type errors across all four files.

Rest of the dashboard src folder (NotificationPreferencesPage, WebhookDashboardPage, ExportHistoryPage, NotificationSearchPage, TemplatePreviewDemoPage, TemplatesPage, ActivityFeed, DeliveryHeatmap, NotificationTimelineView, ThemeToggle, main.tsx) was checked and found clean — no similar corruption.

Fixes CI issue on #419

[drips-wave]

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#352	[Contracts] Add Notification Template Registry	Link to this issue
#372	Emit Event for Subscription Updates	Link to this issue

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