Swift 6 / Concurrency fixes (#578)

* Enable language mode

* WIP

* WIP

* Fix concurrency issues in SmartCardStore

* Switch to SMAppService

* Bump runners

* Base

* Finish Testing migration

* Tweak async for updater

* More

* Backport mutex

* Revert "Backport mutex"

This reverts commit 9b02afb20c.

* WIP

* Reenable

* Fix preview.

* Update package.

* Bump to latest public macOS and Xcode

* Bump back down to 6.1

* Update to Xcode 26.

* Fixed tests.

* More cleanup

* Env fixes

* var->let

* Cleanup

* Persist auth async

* Whitespace.

* Whitespace.

* Cleanup.

* Cleanup

* Redoing locks in actors bc of observable

* Actors.

* .

* Specify b5

* Update package to 6.2

* Fix disabled updater

* Remove preconcurrency warning

* Move updater init

Sources/Secretive/Preview Content/PreviewUpdater.swift

@@ -1,10 +1,11 @@
 import Foundation
-import Combine
+import Observation
 import Brief
 
-class PreviewUpdater: UpdaterProtocol {
+@Observable @MainActor final class PreviewUpdater: UpdaterProtocol {
+
+    var update: Release? = nil
 
-    let update: Release?
     let testBuild = false
 
     init(update: Update = .none) {
@@ -18,6 +19,9 @@ class PreviewUpdater: UpdaterProtocol {
         }
     }
 
+    func ignore(release: Release) async {
+    }
+    
 }
 
 extension PreviewUpdater {