feat: Projektgerüst, Datenmodell und initiale Migration

Schritt 1: src-Layout mit FastAPI-Stack, SQLAlchemy-2.x-Modell inkl.
Buchführung für Kopiermodus und Quarantäne, Alembic-Migration 0001,
strukturierte Logs, CLI (migrate/version), Changelog und Devlog.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+from collections.abc import Iterator
+from pathlib import Path
+
+import pytest
+from sqlalchemy.orm import Session
+
+from netmover.db import make_engine, make_session_factory, upgrade
+
+
+@pytest.fixture
+def db_url(tmp_path: Path) -> str:
+    url = f"sqlite:///{tmp_path / 'test.db'}"
+    upgrade(url)
+    return url
+
+
+@pytest.fixture
+def session(db_url: str) -> Iterator[Session]:
+    engine = make_engine(db_url)
+    factory = make_session_factory(engine)
+    with factory() as s:
+        yield s
+    engine.dispose()