feat: add GitHub issue comments display and AI validation integration

- Add comments section to issue detail panel with lazy loading
- Fetch comments via GraphQL API with pagination (50 at a time)
- Include comments in AI validation analysis when checkbox enabled
- Pass linked PRs info to AI validation for context
- Add "Work in Progress" badge in validation dialog for open PRs
- Add debug logging for validation requests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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

@@ -766,6 +766,8 @@ export class HttpApiClient implements ElectronAPI {
       this.post('/api/github/validation-mark-viewed', { projectPath, issueNumber }),
     onValidationEvent: (callback: (event: IssueValidationEvent) => void) =>
       this.subscribeToEvent('issue-validation:event', callback as EventCallback),
+    getIssueComments: (projectPath: string, issueNumber: number, cursor?: string) =>
+      this.post('/api/github/issue-comments', { projectPath, issueNumber, cursor }),
   };
 
   // Workspace API