Add GitHub integration for PRs, issues and AI PR description (#205)

* feat: integrate GitHub OAuth device flow across runtimes

Add GitHub OAuth device flow endpoints across runtimes
Introduce GitHubSettings UI panel and sidebar entry
Persist GitHub auth state in per-runtime storage

* feat: add GitHub PR status and PR description generation

Show PR status for the current branch in the Git view
Generate a pull request description from the diff between base and head
Expose prStatus, prCreate, and prMerge APIs in web and desktop clients

* feat: add GitHub PR ready for review

Add API to mark pull requests as ready for review
Show a Ready button for draft PRs and reflect status in UI
Handle token expiration and GraphQL errors when marking ready

packages/vscode/webview/api/git.ts

@@ -15,6 +15,7 @@ import type {
   GitDeleteBranchPayload,
   GitDeleteRemoteBranchPayload,
   GeneratedCommitMessage,
+  GeneratedPullRequestDescription,
   GitWorktreeInfo,
   GitAddWorktreePayload,
   GitRemoveWorktreePayload,
@@ -96,6 +97,17 @@ export const createVSCodeGitAPI = (): GitAPI => ({
     };
   },
 
+  generatePullRequestDescription: async (
+    directory: string,
+    payload: { base: string; head: string }
+  ): Promise<GeneratedPullRequestDescription> => {
+    return sendBridgeMessage<GeneratedPullRequestDescription>('api:git/pr-description', {
+      directory,
+      base: payload.base,
+      head: payload.head,
+    });
+  },
+
   listGitWorktrees: async (directory: string): Promise<GitWorktreeInfo[]> => {
     return sendBridgeMessage<GitWorktreeInfo[]>('api:git/worktrees', { directory, method: 'GET' });
   },