ci: add simple test build workflow for Gitea Actions

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

Co-Authored-By: Claude <noreply@anthropic.com>

.gitea/workflows/test-build.yml

@@ -0,0 +1,22 @@
+name: Test Build
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: wsl
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Build archon-server image
+        run: |
+          cd python
+          docker build -f Dockerfile.server -t archon-server:test .
+
+      - name: Show Docker images
+        run: docker images | grep archon