Fix remaining retain cycles, allow coordinators to be weakly referenced and make sure the NavigationStackCoordinator cleans up after itself

ElementX/Sources/Application/CoordinatorProtocol.swift

@@ -17,7 +17,7 @@
 import SwiftUI
 
 @MainActor
-protocol CoordinatorProtocol {
+protocol CoordinatorProtocol: AnyObject {
     func start()
     func stop()
     func toPresentable() -> AnyView

ElementX/Sources/Application/Navigation/NavigationCoordinators.swift

@@ -213,14 +213,14 @@ class NavigationSplitCoordinator: CoordinatorProtocol, ObservableObject, CustomS
     ///
     /// For added complexity, the NavigationSplitCoordinator has an internal compact layout NavigationStack for which we need to manually nil things again
     private func releaseAllCoordinatorReferences() {
-        sidebarModule?.coordinator = nil
-        detailModule?.coordinator = nil
-        sheetModule?.coordinator = nil
-        fullScreenCoverModule?.coordinator = nil
+        sidebarModule?.tearDown()
+        detailModule?.tearDown()
+        sheetModule?.tearDown()
+        fullScreenCoverModule?.tearDown()
         
-        compactLayoutRootModule?.coordinator = nil
+        compactLayoutRootModule?.tearDown()
         compactLayoutStackModules.forEach { module in
-            module.coordinator = nil
+            module.tearDown()
         }
     }
     
@@ -594,6 +594,19 @@ class NavigationStackCoordinator: ObservableObject, CoordinatorProtocol, CustomS
             .presentationDetents(presentationDetents))
     }
     
+    /// The NavigationStack has a tendency to hold on to path items for longer than needed. We work around that by manually nilling the coordinator
+    /// when a NavigationModule is dismissed. As the NavigationModule is just a wrapper multiple instances of it continuing living is of no consequence
+    /// https://stackoverflow.com/questions/73885353/found-a-strange-behaviour-of-state-when-combined-to-the-new-navigation-stack/
+    func stop() {
+        rootModule?.tearDown()
+        sheetModule?.tearDown()
+        fullScreenCoverModule?.tearDown()
+        
+        stackModules.forEach { module in
+            module.tearDown()
+        }
+    }
+    
     // MARK: - CustomStringConvertible
     
     var description: String {

ElementX/Sources/Application/Navigation/NavigationModule.swift

@@ -27,7 +27,7 @@ class NavigationModule: Identifiable, Hashable {
     /// As the NavigationModule is just a wrapper multiple instances of it continuing living is of no consequence
     /// https://stackoverflow.com/questions/73885353/found-a-strange-behaviour-of-state-when-combined-to-the-new-navigation-stack/
     var coordinator: (any CoordinatorProtocol)?
-    let dismissalCallback: (() -> Void)?
+    var dismissalCallback: (() -> Void)?
     
     init(_ coordinator: any CoordinatorProtocol, dismissalCallback: (() -> Void)? = nil) {
         self.coordinator = coordinator
@@ -38,6 +38,7 @@ class NavigationModule: Identifiable, Hashable {
         coordinator?.stop()
         dismissalCallback?()
         coordinator = nil
+        dismissalCallback = nil
     }
     
     nonisolated static func == (lhs: NavigationModule, rhs: NavigationModule) -> Bool {