Added the catalogue models and seed to support phase 4 of the POC prototype in the Persistence package.

Packages/Persistence/Sources/Internal/Migrations/AddListingDeclarations.swift

@@ -0,0 +1,29 @@
+import FluentKit
+
+/// Adds the declared defects and the photos to listings.
+///
+/// Registered ahead of ``SeedCatalogue``, whose model writes both columns.
+struct AddListingDeclarations: AsyncMigration {
+
+    // MARK: Methods
+
+    func prepare(on database: Database) async throws {
+        // One column per update: SQLite adds no more in a single statement.
+        try await database.schema(ListingRecord.schema)
+            .field("defects", .string)
+            .update()
+        try await database.schema(ListingRecord.schema)
+            .field("photos", .string)
+            .update()
+    }
+
+    func revert(on database: Database) async throws {
+        try await database.schema(ListingRecord.schema)
+            .deleteField("photos")
+            .update()
+        try await database.schema(ListingRecord.schema)
+            .deleteField("defects")
+            .update()
+    }
+
+}