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/components/layout/sidebar.tsx

@@ -30,6 +30,7 @@ import {
   useSetupDialog,
   useTrashDialog,
   useProjectTheme,
+  useUnviewedValidations,
 } from './sidebar/hooks';
 
 export function Sidebar() {
@@ -127,6 +128,9 @@ export function Sidebar() {
   // Running agents count
   const { runningAgentsCount } = useRunningAgents();
 
+  // Unviewed validations count
+  const { count: unviewedValidationsCount } = useUnviewedValidations(currentProject);
+
   // Trash dialog and operations
   const {
     showTrashDialog,
@@ -235,6 +239,7 @@ export function Sidebar() {
     setIsProjectPickerOpen,
     cyclePrevProject,
     cycleNextProject,
+    unviewedValidationsCount,
   });
 
   // Register keyboard shortcuts