debug: add CloudKit container diagnostics to sync logs

Logs bundle ID, CKContainer.default() identifier, and iCloud account
status at sync start to help diagnose "Invalid bundle ID for container"
errors on TestFlight.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/SportsTimeApp.swift

@@ -8,6 +8,7 @@
 import SwiftUI
 import SwiftData
 import BackgroundTasks
+import CloudKit
 
 @main
 struct SportsTimeApp: App {
@@ -238,6 +239,21 @@ struct BootstrappedContentView: View {
         let log = SyncLogger.shared
         log.log("🔄 [SYNC] Starting background sync...")
 
+        // Log diagnostic info for debugging CloudKit container issues
+        let bundleId = Bundle.main.bundleIdentifier ?? "unknown"
+        let container = CKContainer.default()
+        let containerId = container.containerIdentifier ?? "unknown"
+        log.log("🔧 [DIAG] Bundle ID: \(bundleId)")
+        log.log("🔧 [DIAG] CKContainer.default(): \(containerId)")
+        if let entitlementContainers = Bundle.main.object(forInfoDictionaryKey: "com.apple.developer.icloud-container-identifiers") as? [String] {
+            log.log("🔧 [DIAG] Entitlement containers: \(entitlementContainers.joined(separator: ", "))")
+        }
+        if let accountStatus = try? await container.accountStatus() {
+            log.log("🔧 [DIAG] iCloud account status: \(accountStatus.rawValue) (0=couldNotDetermine, 1=available, 2=restricted, 3=noAccount)")
+        } else {
+            log.log("🔧 [DIAG] iCloud account status: failed to check")
+        }
+
         // Only reset stale syncInProgress flags; do not clobber an actively running sync.
         let syncState = SyncState.current(in: context)
         if syncState.syncInProgress {