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

src/main.py

@@ -0,0 +1,20 @@
+"""FastAPI application for ZUGFeRD invoice processing."""
+
+import uvicorn
+from fastapi import FastAPI
+
+app = FastAPI(
+    title="ZUGFeRD Service",
+    version="1.0.0",
+    description="REST API for ZUGFeRD invoice extraction and validation",
+)
+
+
+def run(host: str = "0.0.0.0", port: int = 5000) -> None:
+    """Run the FastAPI application.
+
+    Args:
+        host: Host to bind to.
+        port: Port to listen on.
+    """
+    uvicorn.run(app, host=host, port=port)