Fix macOS CI: use workspace dir for Python toolcache instead of sudo

Set AGENT_TOOLSDIRECTORY to a workspace-local path so setup-python
doesn't need /Users/runner or sudo access.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -32,9 +32,11 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Create Python toolcache directory (macOS)
+      - name: Set up Python toolcache (macOS)
         if: matrix.platform == 'macos'
-        run: sudo mkdir -p /Users/runner && sudo chown $USER /Users/runner
+        run: |
+          mkdir -p ${{ github.workspace }}/.toolcache
+          echo "AGENT_TOOLSDIRECTORY=${{ github.workspace }}/.toolcache" >> $GITHUB_ENV
 
       - name: Set up Python
         uses: actions/setup-python@v5