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/desktop/src-tauri/src/assistant_notifications.rs

@@ -267,7 +267,6 @@ async fn handle_question_asked(
     properties: &Value,
     notified_questions: &Mutex<HashSet<String>>,
 ) {
-
     let session_id = properties.get("sessionID").and_then(Value::as_str);
     let question_id = properties.get("id").and_then(Value::as_str);