domain: add Storage & Sources entities (StorageVolume, LibraryPath, IngestSession, Quota)

crates/domain/tests/entities/storage_volume.rs

@@ -0,0 +1,10 @@
+use domain::entities::StorageVolume;
+
+#[test]
+fn creates_read_only_volume() {
+    let vol = StorageVolume::new("archive", "s3://bucket/", false);
+    assert_eq!(vol.volume_name, "archive");
+    assert_eq!(vol.uri_prefix, "s3://bucket/");
+    assert!(!vol.is_writable);
+    assert_eq!(vol.available_bytes, 0);
+}