feat(backup): config et dépendances pour la sauvegarde S3 (#89)

src/backup/config.py

@@ -0,0 +1,26 @@
+from collections.abc import Mapping
+from dataclasses import dataclass
+from pathlib import Path
+
+
+@dataclass(frozen=True)
+class BackupConfig:
+    db_path: Path
+    bucket: str
+    prefix: str
+    endpoint_url: str | None
+    access_key: str
+    secret_key: str
+    encryption_key: str
+
+
+def load_config(env: Mapping[str, str]) -> BackupConfig:
+    return BackupConfig(
+        db_path=Path(env["USERS_DB_PATH"]),
+        bucket=env["S3_BUCKET"],
+        prefix=env.get("S3_BACKUP_PREFIX", "backups"),
+        endpoint_url=env.get("S3_ENDPOINT_URL") or None,
+        access_key=env["S3_ACCESS_KEY_ID"],
+        secret_key=env["S3_SECRET_ACCESS_KEY"],
+        encryption_key=env["BACKUP_ENCRYPTION_KEY"],
+    )