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/Cargo.lock

@@ -2977,7 +2977,7 @@ dependencies = [
 
 [[package]]
 name = "openchamber-desktop"
-version = "1.5.3"
+version = "1.5.5"
 dependencies = [
  "anyhow",
  "axum",