Add camera QR pairing, Bonjour discovery and pinned address recovery

MusicBridge/PlayerStore.swift

@@ -10,6 +10,8 @@ final class PlayerStore: ObservableObject {
     @Published var connected = false
     @Published var busy = false
     @Published var pairing = false
+    @Published var incomingInvitation: String?
+    let discovery = DiscoveryStore()
     private(set) var receivedAt = Date()
     private var client: BridgeClient?
     private var runner: Task<Void, Never>?
@@ -43,7 +45,16 @@ final class PlayerStore: ObservableObject {
 
     func setActive(_ active: Bool) {
         self.active = active
-        if active { resume() } else { stop(); status = "Соединение приостановлено" }
+        if active { discovery.start(); resume() }
+        else { discovery.stop(); stop(); status = "Соединение приостановлено" }
+    }
+
+    func importInvitation(_ text: String) {
+        guard connection == nil, !pairing else {
+            error = "Для подключения другого ПК сначала выберите «Забыть компьютер»."
+            return
+        }
+        incomingInvitation = text
     }
 
     func resume() {
@@ -52,15 +63,26 @@ final class PlayerStore: ObservableObject {
         let current = generation
         runner = Task { [weak self] in
             var delay: UInt64 = 1
+            var attempt = 0
             while !Task.isCancelled {
                 guard let self, self.generation == current else { return }
-                let client = BridgeClient(connection)
+                let saved = self.connection ?? connection
+                let alternatives = self.discovery.computers.compactMap { $0.reconnect(saved) }
+                    .filter { $0.endpoint != saved.endpoint }
+                let candidates = [saved] + alternatives
+                let candidate = candidates[attempt % candidates.count]
+                let client = BridgeClient(candidate)
                 self.client = client
                 self.status = "Подключение к ПК…"
                 do {
                     let initial = try await client.state()
                     try Task.checkCancellation()
                     guard self.generation == current else { client.close(); return }
+                    // Persist a discovered address only after pinned, authenticated HTTPS succeeds.
+                    if candidate.endpoint != saved.endpoint {
+                        try KeychainStore.save(candidate)
+                        self.connection = candidate
+                    }
                     self.accept(initial, client: client)
                     client.openEvents()
                     // Abort a silent/stalled stream even if the OS has not detected a lost Wi-Fi link.
@@ -94,6 +116,7 @@ final class PlayerStore: ObservableObject {
                     }
                     self.status = "ПК недоступен. Повтор через \(delay) с"
                     self.error = error.localizedDescription
+                    attempt += 1
                 }
                 do { try await Task.sleep(nanoseconds: delay * 1_000_000_000) } catch { return }
                 delay = min(delay * 2, 16)