feat: Add validation viewing functionality and UI updates

- Implemented a new function to mark validations as viewed by the user, updating the validation state accordingly.
- Added a new API endpoint for marking validations as viewed, integrated with the existing GitHub routes.
- Enhanced the sidebar to display the count of unviewed validations, providing real-time updates.
- Updated the GitHub issues view to mark validations as viewed when issues are accessed, improving user interaction.
- Introduced a visual indicator for unviewed validations in the issue list, enhancing user awareness of pending validations.

apps/ui/src/lib/http-api-client.ts

@@ -762,6 +762,8 @@ export class HttpApiClient implements ElectronAPI {
       this.post('/api/github/validation-stop', { projectPath, issueNumber }),
     getValidations: (projectPath: string, issueNumber?: number) =>
       this.post('/api/github/validations', { projectPath, issueNumber }),
+    markValidationViewed: (projectPath: string, issueNumber: number) =>
+      this.post('/api/github/validation-mark-viewed', { projectPath, issueNumber }),
     onValidationEvent: (callback: (event: IssueValidationEvent) => void) =>
       this.subscribeToEvent('issue-validation:event', callback as EventCallback),
   };