Stemify iOS 1.1 and WebUI updates, repo restructure into desktop/ios/server/web

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ios/Shared/WidgetShared.swift

@@ -0,0 +1,58 @@
+import Foundation
+
+/// One stem as the widgets draw it. [level] is the fader position (0.8 is unity), [percent] the gain the mixer shows.
+struct WidgetStem: Codable, Hashable, Identifiable {
+    var name: String
+    var label: String
+    var color: UInt32
+    var level: Double
+    var percent: Int
+    var muted = false
+    var solo = false
+    var id: String { name }
+}
+
+/// What's playing and how it's mixed, written by the app for the widgets and the lock screen control.
+struct WidgetSnapshot: Codable, Equatable {
+    var title = ""
+    var artist = ""
+    /// The current mix ("Karaoke", "Custom Mix"…), empty unless stems are playing.
+    var mix = ""
+    /// What the Mix button moves to.
+    var next = ""
+    var playing = false
+    /// Empty unless stems are playing.
+    var stems: [WidgetStem] = []
+    /// The art key the saved artwork belongs to, nil while it isn't saved yet.
+    var art: String?
+
+    var hasTrack: Bool { !title.isEmpty }
+    var hasStems: Bool { !stems.isEmpty }
+    /// Muted, or left out by another stem's solo.
+    func silent(_ s: WidgetStem) -> Bool { s.muted || stems.contains(where: \.solo) && !s.solo }
+}
+
+enum WidgetStore {
+    static let group = "group.org.cdnutter.stemify"
+    static let mixerKind = "org.cdnutter.stemify.mixer"
+    static let mixKind = "org.cdnutter.stemify.mix"
+    static let controlKind = "org.cdnutter.stemify.mix-control"
+    private static let key = "widgetSnapshot"
+
+    /// Without the App Group (some sideloading tools drop it) this is a private store and the widgets show Nothing Playing.
+    private static var defaults: UserDefaults? { UserDefaults(suiteName: group) }
+
+    static var artURL: URL? {
+        FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: group)?.appendingPathComponent("art.jpg")
+    }
+
+    static func load() -> WidgetSnapshot {
+        guard let d = defaults?.data(forKey: key), let s = try? JSONDecoder().decode(WidgetSnapshot.self, from: d) else { return WidgetSnapshot() }
+        return s
+    }
+
+    static func save(_ s: WidgetSnapshot) {
+        guard let d = try? JSONEncoder().encode(s) else { return }
+        defaults?.set(d, forKey: key)
+    }
+}