feat: Add Gitea Actions CI/CD for Docker image build

- Add .gitea/workflows/build.yml for automated builds on tag push
- Update docker-compose.yml to pull from Gitea Registry
- Add docker-compose.build.yml for local development builds

Build triggers on tags matching 'v*' (e.g., v1.0.0)
Images pushed to gitea.likegears.com/likegears/material_texture

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,8 +1,6 @@
 services:
   app:
-    build:
-      context: .
-      dockerfile: Dockerfile
+    image: gitea.likegears.com/likegears/material_texture:latest
     ports:
       - "8081:8080"
     environment: