Add Docker build with Gitea Actions CI

- Add Dockerfile with Python 3.13 + uv
- Add Gitea Actions workflow for auto-build on push
- Add deposit_api.py for balance management
- Update api_server.py with domain registration endpoint

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

Dockerfile

@@ -0,0 +1,21 @@
+FROM python:3.13-slim
+
+WORKDIR /app
+
+# Install uv
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
+# Copy dependency files first (for layer caching)
+COPY pyproject.toml uv.lock ./
+
+# Install dependencies
+RUN uv sync --frozen --no-dev
+
+# Copy application code
+COPY *.py ./
+
+# Expose port
+EXPOSE 8000
+
+# Run the API server
+CMD ["uv", "run", "python", "api_server.py"]