Run lint on Linux with prebuilt swiftformat binary

Downloads the prebuilt Linux binary from SwiftFormat releases
instead of building from source or requiring macOS.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: kylehowells

.github/workflows/test.yml

@@ -49,15 +49,18 @@ jobs:
       - name: Run tests
         run: swift test
 
-  # Lint - only runs on tag pushes (releases)
+  # Lint - runs on every push (Linux)
   lint:
-    runs-on: macos-latest
-    if: startsWith(github.ref, 'refs/tags/')
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
 
       - name: Install swiftformat
-        run: brew install swiftformat
+        run: |
+          wget -q https://github.com/nicklockwood/SwiftFormat/releases/download/0.54.6/swiftformat_linux.zip
+          unzip -q swiftformat_linux.zip
+          chmod +x swiftformat_linux
+          sudo mv swiftformat_linux /usr/local/bin/swiftformat
 
       - name: Lint
         run: swiftformat --lint . --reporter github-actions-log