feat(project): initialize ZUGFeRD service with pyproject.toml and directory structure

tests/__init__.py

@@ -0,0 +1 @@
+"""Test suite for ZUGFeRD service."""

tests/conftest.py

@@ -0,0 +1,9 @@
+"""Pytest configuration and shared fixtures."""
+
+import pytest
+
+
+@pytest.fixture
+def sample_pdf_bytes():
+    """Fixture providing sample PDF bytes for testing."""
+    return b"%PDF-1.4\n%fake pdf content for testing\n%%EOF"