ci: use macos-26-intel for x86_64 target

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: branchseer

.github/workflows/ci.yml

@@ -53,7 +53,7 @@ jobs:
             target: x86_64-pc-windows-msvc
           - os: macos-latest
             target: aarch64-apple-darwin
-          - os: macos-13
+          - os: macos-26-intel
             target: x86_64-apple-darwin
     runs-on: ${{ matrix.os }}
     steps: