fix: add GitHub server check to workflows and streamline CMake installation

.github/workflows/macos.yml

@@ -14,16 +14,11 @@ on:
 
 jobs:
   build-dmg:
+    # Only run on GitHub, skip on Gitea
+    if: github.server_url == 'https://github.com'
     runs-on: macos-latest
 
     steps:
-      - name: Check if running on macOS
-        run: |
-          if [[ "$(uname)" != "Darwin" ]]; then
-            echo "::error::This workflow requires a real macOS runner, not Docker"
-            exit 1
-          fi
-
       - uses: actions/checkout@v2
         with:
           submodules: 'true'
@@ -65,4 +60,4 @@ jobs:
         uses: actions/upload-artifact@v4
         with:
           name: VoxelEngineMacOs
-          path: VoxelEngineMacApp.dmg
+          path: VoxelEngineMacApp.dmg