Use a compile gate for Windows Rust CI

Compile every target on Windows without linking the unit-test harnesses,
which require packaged SDL and Lua libraries. Keep the full Rust test suite
on Ubuntu.

Author: mtdowling

.github/workflows/ci.yml

@@ -21,7 +21,10 @@ jobs:
             - uses: actions/checkout@v4
             - run: cargo fmt --all -- --check
             - run: cargo clippy --locked --workspace --all-targets -- -D warnings
-            - run: cargo test --locked --workspace --all-targets
+            - if: runner.os == 'Windows'
+              run: cargo check --locked --workspace --all-targets
+            - if: runner.os != 'Windows'
+              run: cargo test --locked --workspace --all-targets
 
     engine:
         runs-on: macos-15