Propagate request context in block REST handlers.

Use r.Context() for DB query timeouts so client disconnects cancel in-flight block lookups instead of running against a detached background context.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/api/rest/blocks.go

@@ -21,7 +21,7 @@ func (s *Server) handleGetBlockByNumber(w http.ResponseWriter, r *http.Request,
 	}
 
 	// Add query timeout
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
 	defer cancel()
 
 	query := `
@@ -89,7 +89,7 @@ func (s *Server) handleGetBlockByHash(w http.ResponseWriter, r *http.Request, ha
 	}
 
 	// Add query timeout
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
 	defer cancel()
 
 	query := `