fix: leverage windows-11-arm for Windows ARM builds (#3062)

This is in support of https://github.com/openai/codex/issues/2979.

Once we have a release out, we can update the npm module and the VS Code
extension to take advantage of this.

.github/workflows/rust-ci.yml

@@ -100,6 +100,9 @@ jobs:
           - runner: windows-latest
             target: x86_64-pc-windows-msvc
             profile: dev
+          - runner: windows-11-arm
+            target: aarch64-pc-windows-msvc
+            profile: dev
 
           # Also run representative release builds on Mac and Linux because
           # there could be release-only build errors we want to catch.
@@ -114,6 +117,9 @@ jobs:
           - runner: windows-latest
             target: x86_64-pc-windows-msvc
             profile: release
+          - runner: windows-11-arm
+            target: aarch64-pc-windows-msvc
+            profile: release
 
     steps:
       - uses: actions/checkout@v5