Added the catalogue models and seed to support phase 3 of the POC prototype in the Persistence package.

Packages/Persistence/Sources/Public/Enumerations/TradeError.swift

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+/// Why a step towards a sale was turned down.
+public enum TradeError: Error, Equatable, Sendable {
+    /// The amount is not a positive number of cents at or under the asking price.
+    case invalidAmount
+    /// The listing does not exist, or is sold.
+    case listingUnavailable
+    /// The account is not a party to the conversation, offer, or sale — or the step is not theirs to take now.
+    case notAllowed
+    /// The buyer already has an open offer on the listing.
+    case offerAlreadyOpen
+    /// The offer is under the floor the seller hears offers from, in euro cents.
+    case offerTooLow(floorCents: Int)
+    /// The listing's seller takes no offers.
+    case offersNotAccepted
+    /// The listing, shop, conversation, or sale belongs to the account itself.
+    case ownListing
+    /// The shop has no owner to sell on its behalf.
+    case shopUnattended
+}