fix: address self-review NIT findings on PR #93

- Add timer.Stop() on happy path in retry loop (idiomatic)
- Add concurrency caveat to Client doc comment for SetHTTPClient/SetRetryBackoff
- Add explicit 'stale'/'waiting' cases to mapCheckRunStatus

github/client.go

@@ -66,7 +66,8 @@ func asAPIError(err error) (*APIError, bool) {
 }
 
 // Client interacts with the GitHub API.
-// A Client is safe for concurrent use by multiple goroutines.
+// A Client is safe for concurrent use by multiple goroutines;
+// however, SetHTTPClient and SetRetryBackoff must not be called concurrently with requests.
 type Client struct {
 	baseURL string
 	token   string
@@ -145,6 +146,7 @@ func (c *Client) doRequest(ctx context.Context, method, url string, accept strin
 				timer := time.NewTimer(delay)
 				select {
 				case <-timer.C:
+					timer.Stop()
 				case <-ctx.Done():
 					timer.Stop()
 					return nil, ctx.Err()

github/pr.go

@@ -220,6 +220,8 @@ func mapCheckRunStatus(conclusion *string, _ string) string {
 		return "failure"
 	case "cancelled", "skipped", "neutral":
 		return "success" // non-blocking
+	case "stale", "waiting":
+		return "pending"
 	default:
 		return "pending"
 	}