feat: automatic backup on launch, foreground, and photo library change

AutoBackupCoordinator (new):
- @MainActor singleton that owns all auto-backup decisions
- Phase model: idle / checking / autoBackingUp / disconnected
  - idle:          nothing pending or destination not set
  - checking:      reconciliation in progress before decision
  - autoBackingUp: coordinator-triggered BackupEngine run active
  - disconnected:  NAS offline, pending count queued for retry
- Combine subscription on BackupStatusService.$isRefreshing fires
  handleReconciliationComplete() on every reconcile completion — the
  single entry point for all auto-backup decisions
- Combine subscription on LANMonitor.$nasReachable fires
  handleNASReachable() which retries only when phase == .disconnected
- Guards: autoBackupEnabled, quiet hours, chargingOnlyMode + battery state
- canAutoBackup also blocks when engine.job.status.isActive to prevent
  double-start from concurrent photo library change + foreground events

BackupView:
- .task + .onChange(of: scenePhase) now call coordinator.onActive() instead
  of statusService.refresh() directly — coordinator decides whether to also
  start a backup after reconciliation completes
- ringContentID includes coordinator phase suffix → ring animates on
  checking/disconnected transitions
- ringCenterContent case 0: when engine is idle, shows:
  - disconnectedRingView if phase == .disconnected and needBackup > 0
    (wifi.slash icon, "Waiting for NAS", queued count)
  - checkingRingView if phase == .checking (spinner, "Checking…")
  - existing ringMainView otherwise
- ringColor: dim orange (0.35 opacity) when disconnected with pending items
- Pull-to-refresh reconciliation triggers auto-backup via Combine chain

ConnectionStore:
- autoBackupEnabled: Bool, default true, UserDefaults-persisted

SettingsView:
- AUTO BACKUP section at top with autoBackupEnabled toggle

BackgroundTaskManager:
- BGProcessingTask: quiet-hours guard, requiresExternalPower mirrors
  chargingOnlyMode, expiration handler calls engine.cancel() for clean exit
- BGAppRefreshTask: lightweight refresh only (no upload in background refresh)
- Both tasks reschedule themselves before doing any work

AppDelegate:
- UIDevice.current.isBatteryMonitoringEnabled = true for battery checks

NASBackupApp:
- AutoBackupCoordinator.shared injected as @StateObject + environmentObject

Co-Authored-By: Kutesir <kutesir@provoc.ug>
Co-Authored-By: Sentry <sentry@provoc.ug>

Services/AutoBackupCoordinator.swift

@@ -0,0 +1,167 @@
+import Foundation
+import Combine
+import UIKit
+import os.log
+
+private let log = Logger(subsystem: "com.albert.nasbackup", category: "AutoBackup")
+
+/// Decides when to start backup automatically and tracks the high-level app phase.
+///
+/// Phase model:
+///   idle         — no pending work, or destination not configured
+///   checking     — reconciliation running, awaiting the pending-queue size
+///   autoBackingUp — coordinator-triggered backup running
+///   disconnected — NAS offline while items are queued; will retry when reachable
+///
+/// Active-backup states (running/paused/completed/failed) are owned by BackupEngine.job
+/// and are read directly by BackupView — the coordinator does not duplicate them.
+@MainActor
+final class AutoBackupCoordinator: ObservableObject {
+    static let shared = AutoBackupCoordinator()
+
+    enum Phase: Equatable {
+        case idle
+        case checking
+        case autoBackingUp
+        case disconnected
+    }
+
+    @Published private(set) var phase: Phase = .idle
+    @Published private(set) var pendingAtDisconnect: Int = 0
+
+    private let engine        = BackupEngine.shared
+    private let statusService = BackupStatusService.shared
+    private let store         = ConnectionStore.shared
+    private let lanMonitor    = LANMonitor.shared
+
+    private var cancellables = Set<AnyCancellable>()
+
+    // MARK: — Init
+
+    private init() {
+        setupObservation()
+    }
+
+    private func setupObservation() {
+        // Fires when reconciliation transitions from running → done.
+        // dropFirst() skips the initial subscription value so we don't fire on
+        // startup before the first real reconciliation has run.
+        statusService.$isRefreshing
+            .dropFirst()
+            .filter { !$0 }
+            .receive(on: RunLoop.main)
+            .sink { [weak self] _ in self?.handleReconciliationComplete() }
+            .store(in: &cancellables)
+
+        // Fires when NAS transitions to reachable — only acts when in .disconnected phase
+        // so we don't duplicate the trigger on initial startup or during active backup.
+        lanMonitor.$nasReachable
+            .dropFirst()
+            .compactMap { $0 }
+            .filter { $0 }
+            .receive(on: RunLoop.main)
+            .sink { [weak self] _ in self?.handleNASReachable() }
+            .store(in: &cancellables)
+    }
+
+    // MARK: — External triggers
+
+    /// Call when the app becomes active: on first launch, foreground resume, or session unlock.
+    /// Safe to call repeatedly — guards prevent redundant reconciliation.
+    func onActive() {
+        guard !engine.job.status.isActive else { return }
+        guard store.savedConnection != nil else { return }
+        phase = .checking
+        statusService.refresh(force: true)
+        // handleReconciliationComplete() fires via Combine when the refresh settles
+    }
+
+    // MARK: — Combine handlers
+
+    private func handleReconciliationComplete() {
+        let snapshot = statusService.snapshot
+
+        // No destination configured yet
+        guard let conn = store.savedConnection, conn.remotePath != "/" else {
+            phase = .idle
+            return
+        }
+
+        // Nothing to back up — clear any stale state
+        guard snapshot.needBackup > 0 else {
+            phase = .idle
+            pendingAtDisconnect = 0
+            return
+        }
+
+        // NAS offline — queue pending count and wait for reachability
+        if snapshot.connectionState == .offline {
+            pendingAtDisconnect = snapshot.needBackup
+            phase = .disconnected
+            log.info("NAS offline — \(snapshot.needBackup) items queued")
+            return
+        }
+
+        // Auto-backup setting is off — show count but don't start
+        guard store.autoBackupEnabled else {
+            phase = .idle
+            return
+        }
+
+        triggerAutoBackupIfNeeded(conn: conn)
+    }
+
+    private func handleNASReachable() {
+        guard case .disconnected = phase else { return }
+        log.info("NAS reachable again — rescheduling auto-check")
+        onActive()
+    }
+
+    // MARK: — Auto-backup trigger
+
+    private func triggerAutoBackupIfNeeded(conn: NASConnection) {
+        guard canAutoBackup else { return }
+
+        let pending = statusService.snapshot.needBackup
+        log.info("Auto-backup triggered: \(pending) pending items → \(conn.remotePath)")
+
+        phase = .autoBackingUp
+        pendingAtDisconnect = 0
+
+        Task {
+            do {
+                _ = try await engine.run(connection: conn, filter: store.backupFilter)
+            } catch {
+                log.error("Auto-backup error: \(error.localizedDescription)")
+            }
+            // engine.run() calls refreshAfterBackup() which triggers reconciliation.
+            // handleReconciliationComplete() will fire again and reset phase.
+            if case .autoBackingUp = phase { phase = .idle }
+        }
+    }
+
+    // MARK: — Guards
+
+    private var canAutoBackup: Bool {
+        // Already running
+        guard !engine.job.status.isActive else { return false }
+        // Quiet hours
+        guard !store.isInQuietHours else {
+            log.info("Auto-backup skipped — quiet hours active")
+            return false
+        }
+        // Charging-only mode
+        guard isBatteryOK else {
+            log.info("Auto-backup skipped — not charging (chargingOnlyMode enabled)")
+            return false
+        }
+        return true
+    }
+
+    private var isBatteryOK: Bool {
+        guard store.chargingOnlyMode else { return true }
+        let state = UIDevice.current.batteryState
+        // .unknown covers simulator and unavailable reads — allow in those cases
+        return state == .charging || state == .full || state == .unknown
+    }
+}