feat: add GitHub issue picker and API endpoints

Add GitHubIssuePickerDialog UI for selecting issues
Enable new session from GitHub issue from session sidebar
Implement GitHub issues/list/get/comments APIs across desktop, web, and VS Code

packages/desktop/src/api/github.ts

@@ -1,6 +1,9 @@
 import type {
   GitHubAPI,
   GitHubAuthStatus,
+  GitHubIssueCommentsResult,
+  GitHubIssueGetResult,
+  GitHubIssuesListResult,
   GitHubPullRequest,
   GitHubPullRequestCreateInput,
   GitHubPullRequestMergeInput,
@@ -59,4 +62,19 @@ export const createDesktopGitHubAPI = (): GitHubAPI => ({
     const { safeInvoke } = await import('../lib/tauriCallbackManager');
     return safeInvoke<GitHubPullRequestReadyResult>('github_pr_ready', payload, { timeout: 20000 });
   },
+
+  async issuesList(directory: string): Promise<GitHubIssuesListResult> {
+    const { safeInvoke } = await import('../lib/tauriCallbackManager');
+    return safeInvoke<GitHubIssuesListResult>('github_issues_list', { directory }, { timeout: 20000 });
+  },
+
+  async issueGet(directory: string, number: number): Promise<GitHubIssueGetResult> {
+    const { safeInvoke } = await import('../lib/tauriCallbackManager');
+    return safeInvoke<GitHubIssueGetResult>('github_issue_get', { directory, number }, { timeout: 20000 });
+  },
+
+  async issueComments(directory: string, number: number): Promise<GitHubIssueCommentsResult> {
+    const { safeInvoke } = await import('../lib/tauriCallbackManager');
+    return safeInvoke<GitHubIssueCommentsResult>('github_issue_comments', { directory, number }, { timeout: 20000 });
+  },
 });