[#1334] make CI Windows build use ninja

Author: schaubh

.github/actions/build/action.yml

@@ -42,6 +42,11 @@ runs:
           pip install -r requirements.txt -r requirements_dev.txt
         fi
 
+    - name: Install Ninja
+      if: ${{ runner.os == 'Windows' }}
+      shell: bash
+      run: pip install ninja
+
     - name: Setup sccache
       uses: mozilla/sccache-action@v0.0.9
 
@@ -51,6 +56,9 @@ runs:
         echo "SCCACHE_GHA_ENABLED=true" >> $GITHUB_ENV
         echo "CMAKE_C_COMPILER_LAUNCHER=sccache" >> $GITHUB_ENV
         echo "CMAKE_CXX_COMPILER_LAUNCHER=sccache" >> $GITHUB_ENV
+        if [[ "${{ runner.os }}" == 'Windows' ]]; then
+          echo "CMAKE_BUILD_PARALLEL_LEVEL=$(python -c 'import os; print(os.cpu_count() or 1)')" >> $GITHUB_ENV
+        fi
 
     - name: Cache Conan
       uses: actions/cache@v4
@@ -72,10 +80,6 @@ runs:
            printf "tools.system.package_manager:mode=install\n" >> "$prof_path"
         grep -q '^tools.system.package_manager:sudo=True$' "$prof_path" || \
           printf "tools.system.package_manager:sudo=True\n" >> "$prof_path"
-        if [[ "${{ runner.os }}" == 'Windows' ]]; then
-          grep -q '^tools.microsoft.msbuild:max_cpu_count=0$' "$prof_path" || \
-            printf "tools.microsoft.msbuild:max_cpu_count=0\n" >> "$prof_path"
-        fi
 
     - name: Build Basilisk
       shell: bash

.github/workflows/pull-request.yml

@@ -50,7 +50,7 @@ jobs:
       - uses: ./.github/actions/build
         with:
           python-version: 3.14
-          conan-args: --opNav True --mujoco True --mujocoReplay True
+          conan-args: --opNav True --mujoco True --mujocoReplay True --generator Ninja
       - name: Pytest
         shell: pwsh
         working-directory: src