Restore pasting and rename sections to workspaces

Replacing the main menu dropped the Edit menu that AppKit routes
Cmd+V/C/A/Z through, so the composer could not paste at all. The menu is
rebuilt with those items, which --diag now dumps so the wiring can be
checked without a keyboard.

Workspaces also gained an order: the Cmd+K switcher has up/down controls,
creating one opens a naming modal instead of prefilling the composer, and
the UI now says workspace throughout. The stored JSON keeps the original
`sections` keys so existing data and sync payloads stay valid.

Sources/Prompt/Store.swift

@@ -38,11 +38,17 @@ final class Store: ObservableObject {
     private let storeFile: URL
     private let imageCache = NSCache<NSString, NSImage>()
 
-    init() {
-        let appSupport = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
-        directory = appSupport.appendingPathComponent("Prompt", isDirectory: true)
-        imagesDirectory = directory.appendingPathComponent("Images", isDirectory: true)
-        storeFile = directory.appendingPathComponent("store.json")
+    /// `directory` is injectable so the store can be exercised against a
+    /// scratch folder instead of the user's real data.
+    init(directory: URL? = nil) {
+        if let directory {
+            self.directory = directory
+        } else {
+            let appSupport = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
+            self.directory = appSupport.appendingPathComponent("Prompt", isDirectory: true)
+        }
+        imagesDirectory = self.directory.appendingPathComponent("Images", isDirectory: true)
+        storeFile = self.directory.appendingPathComponent("store.json")
 
         try? FileManager.default.createDirectory(at: imagesDirectory, withIntermediateDirectories: true)
         load()
@@ -130,6 +136,18 @@ final class Store: ObservableObject {
         return section
     }
 
+    /// Reorders a workspace within the list. The UI calls these "workspaces";
+    /// the model and the persisted JSON keep the original `sections` naming so
+    /// existing stores and sync payloads keep working.
+    func moveSection(_ id: UUID, by offset: Int) {
+        guard let index = sections.firstIndex(where: { $0.id == id }) else { return }
+        let target = index + offset
+        guard sections.indices.contains(target) else { return }
+        let section = sections.remove(at: index)
+        sections.insert(section, at: target)
+        save()
+    }
+
     // MARK: - Items
 
     @discardableResult