Implemented phase 5 for the POC prototype in the Website service.

Services/Website/Sources/Library/Internal/Extensions/String+Routes.swift

@@ -3,14 +3,12 @@ import Foundation
 extension String {
     /// A namespace for the paths of the site's screens.
     ///
-    /// Screens not built yet are listed too, and answer with the not-found page until they are.
+    /// Single-sourced, so the navigation and the controllers never spell a path differently.
     enum Route {
         /// The account screen.
         static let account = "/account"
-        /// The collection tracker.
-        static let collection = "/collection"
-        /// The events screen.
-        static let events = "/events"
+        /// The side-by-side comparison of copies.
+        static let compare = "/compare"
         /// The public grading guide.
         static let gradingGuide = "/grading-guide"
         /// The browse / home screen.
@@ -19,26 +17,20 @@ extension String {
         static let messages = "/messages"
         /// The open-a-shop onboarding.
         static let openShop = "/sell/open-a-shop"
-        /// The privacy statement.
-        static let privacy = "/privacy"
-        /// The passkey recovery screen.
-        static let recover = "/recover"
         /// The search results screen.
         static let search = "/search"
         /// The seller dashboard.
         static let sellerDashboard = "/sell"
-        /// The rules sellers agree to.
-        static let sellerRules = "/seller-rules"
         /// The series index.
         static let series = "/series"
         /// The passkey sign-in screen.
         static let signIn = "/sign-in"
         /// The path a sign-out is posted to.
         static let signOut = "/sign-out"
-        /// The terms of service.
-        static let terms = "/terms"
         /// The want list.
         static let wants = "/wants"
+        /// The first-sign-in screen.
+        static let welcome = "/welcome"
 
         /// The path an offer is answered at.
         /// - Parameter id: the offer's identifier.
@@ -117,6 +109,17 @@ extension String {
             "/sales/\(number)"
         }
 
+        /// The path of a series' screen, optionally on the copies of one issue.
+        /// - Parameters:
+        ///   - slug: the series' URL slug.
+        ///   - issue: the issue whose copies are listed, or `nil` (the default) for none.
+        static func series(
+            _ slug: String,
+            issue: Int? = nil
+        ) -> String {
+            "\(series)/\(slug)\(issue.map { "?issue=\($0)" } ?? "")"
+        }
+
         /// The path of a shop's public screen.
         /// - Parameter slug: the shop's URL slug.
         static func shop(
@@ -146,6 +149,25 @@ extension String {
             return path
         }
 
+        /// The path of the first-sign-in screen, continuing to the given path afterwards.
+        static func welcome(
+            returningTo path: String
+        ) -> String {
+            "\(welcome)?return=\(path.addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? "")"
+        }
+
+        /// The path of the form adding a want, filled from a listing or with a title.
+        static func newWant(
+            listing slug: String? = nil,
+            title: String? = nil
+        ) -> String {
+            let query = [slug.map { "listing=\($0)" }, title.map { "title=\($0.addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? "")" }]
+                .compactMap(\.self)
+                .joined(separator: "&")
+
+            return "\(wants)/new\(query.isEmpty ? "" : "?\(query)")"
+        }
+
         /// The path of the sign-in screen, returning to the given path afterwards.
         /// - Parameter path: the path the visitor's gated action started from.
         static func signIn(