fix(apple/tvOS): system-style slide for in-stack pushes (swiftui-navigation-transitions)

SwiftUI's NavigationStack on tvOS animates pushes as a bare crossfade with no public
customization — the system Settings app slides. The home stack now applies
.customNavigationTransition(.slide) on tvOS via davdroman/swiftui-navigation-transitions
(MIT, tvOS 13+), covering the top-level routes AND the settings pickers' drill-ins.

The dependency is referenced by the Xcode PROJECT only and linked solely by the
Punktfunk-tvOS target: its manifest (no macOS platform declared vs 10.15 deps) breaks
SwiftPM whole-graph validation for plain `swift build`, and the #if os(tvOS) import
never compiles in the macOS-only SwiftPM dev shell anyway. Headless builds need
xcodebuild -skipMacroValidation (the lib pulls Swift macro packages; in the Xcode UI
it's a one-time Trust & Enable prompt).

iOS/macOS keep their untouched system navigation animations.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/Package.swift

@@ -24,6 +24,9 @@ let package = Package(
             ]
         ),
         // Development app shell (swift run PunktfunkClient): connect form → stream + input.
+        // (The tvOS slide-transition package is referenced by the Xcode PROJECT only —
+        // its manifest breaks SwiftPM whole-graph validation on macOS, and only the
+        // Punktfunk-tvOS target links it; the #if os(tvOS) import never compiles here.)
         .executableTarget(name: "PunktfunkClient", dependencies: ["PunktfunkKit"]),
         .testTarget(name: "PunktfunkKitTests", dependencies: ["PunktfunkKit"]),
     ]

clients/apple/Punktfunk.xcodeproj/project.pbxproj

@@ -10,6 +10,7 @@
 		AA0000000000000000000005 /* PunktfunkKit in Frameworks */ = {isa = PBXBuildFile; productRef = AA0000000000000000000006 /* PunktfunkKit */; };
 		BB0000000000000000000005 /* PunktfunkKit in Frameworks */ = {isa = PBXBuildFile; productRef = BB0000000000000000000006 /* PunktfunkKit */; };
 		CC0000000000000000000005 /* PunktfunkKit in Frameworks */ = {isa = PBXBuildFile; productRef = CC0000000000000000000006 /* PunktfunkKit */; };
+		DD0000000000000000000003 /* SwiftUINavigationTransitions in Frameworks */ = {isa = PBXBuildFile; productRef = DD0000000000000000000002 /* SwiftUINavigationTransitions */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -53,6 +54,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				CC0000000000000000000005 /* PunktfunkKit in Frameworks */,
+				DD0000000000000000000003 /* SwiftUINavigationTransitions in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -148,6 +150,7 @@
 			name = "Punktfunk-tvOS";
 			packageProductDependencies = (
 				CC0000000000000000000006 /* PunktfunkKit */,
+				DD0000000000000000000002 /* SwiftUINavigationTransitions */,
 			);
 			productName = "Punktfunk-tvOS";
 			productReference = CC0000000000000000000001 /* Punktfunk-tvOS.app */;
@@ -177,6 +180,7 @@
 			mainGroup = AA0000000000000000000007;
 			packageReferences = (
 				AA000000000000000000000F /* XCLocalSwiftPackageReference "." */,
+				DD0000000000000000000001 /* XCRemoteSwiftPackageReference "swiftui-navigation-transitions" */,
 			);
 			preferredProjectObjectVersion = 77;
 			productRefGroup = AA0000000000000000000008 /* Products */;
@@ -588,6 +592,17 @@
 		};
 /* End XCLocalSwiftPackageReference section */
 
+/* Begin XCRemoteSwiftPackageReference section */
+		DD0000000000000000000001 /* XCRemoteSwiftPackageReference "swiftui-navigation-transitions" */ = {
+			isa = XCRemoteSwiftPackageReference;
+			repositoryURL = "https://github.com/davdroman/swiftui-navigation-transitions";
+			requirement = {
+				kind = upToNextMajorVersion;
+				minimumVersion = 0.18.0;
+			};
+		};
+/* End XCRemoteSwiftPackageReference section */
+
 /* Begin XCSwiftPackageProductDependency section */
 		AA0000000000000000000006 /* PunktfunkKit */ = {
 			isa = XCSwiftPackageProductDependency;
@@ -601,6 +616,11 @@
 			isa = XCSwiftPackageProductDependency;
 			productName = PunktfunkKit;
 		};
+		DD0000000000000000000002 /* SwiftUINavigationTransitions */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = DD0000000000000000000001 /* XCRemoteSwiftPackageReference "swiftui-navigation-transitions" */;
+			productName = SwiftUINavigationTransitions;
+		};
 /* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = AA000000000000000000000D /* Project object */;

clients/apple/Punktfunk.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -0,0 +1,60 @@
+{
+  "originHash" : "5d17a752eb57d190a90cbd663718ff44034b24fe0ae1baafea7677db2d49da6f",
+  "pins" : [
+    {
+      "identity" : "objc-runtime-tools",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/davdroman/objc-runtime-tools",
+      "state" : {
+        "revision" : "04715d0c98d366d7000be32c0c81b4ba87001910",
+        "version" : "0.5.1"
+      }
+    },
+    {
+      "identity" : "swift-once-macro",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/davdroman/swift-once-macro",
+      "state" : {
+        "revision" : "5f9d4e77cd95335fe14b44064fcf7f96e8ed56a0",
+        "version" : "1.1.1"
+      }
+    },
+    {
+      "identity" : "swift-syntax",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/swiftlang/swift-syntax",
+      "state" : {
+        "revision" : "79e4b74a295b6eb74a8b585e3a39d29e70c1dbd1",
+        "version" : "603.0.2"
+      }
+    },
+    {
+      "identity" : "swiftui-introspect",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/siteline/swiftui-introspect",
+      "state" : {
+        "revision" : "aead9358a55f635d62d885aeb9105752c0213aec",
+        "version" : "27.0.0-beta.1"
+      }
+    },
+    {
+      "identity" : "swiftui-navigation-transitions",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/davdroman/swiftui-navigation-transitions",
+      "state" : {
+        "revision" : "78287a0adf2ed35c40dc6445d0c7fc6fba236076",
+        "version" : "0.18.0"
+      }
+    },
+    {
+      "identity" : "xctest-dynamic-overlay",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/pointfreeco/xctest-dynamic-overlay",
+      "state" : {
+        "revision" : "cb281f343fd953280336dcbd3822cdf47c182f5b",
+        "version" : "1.10.0"
+      }
+    }
+  ],
+  "version" : 3
+}

clients/apple/Sources/PunktfunkClient/ContentView.swift

@@ -13,6 +13,9 @@ import AppKit
 #endif
 import PunktfunkKit
 import SwiftUI
+#if os(tvOS)
+import SwiftUINavigationTransitions
+#endif
 
 struct ContentView: View {
     @StateObject private var model = SessionModel()
@@ -181,6 +184,11 @@ struct ContentView: View {
         #if os(macOS)
         .frame(minWidth: 480, minHeight: 360)
         #endif
+        #if os(tvOS)
+        // The Settings-app slide for every push in this stack (top-level routes AND
+        // the pickers' drill-ins) — SwiftUI's default on tvOS is a bare crossfade.
+        .customNavigationTransition(.slide)
+        #endif
         #if !os(tvOS)
         .sheet(isPresented: $showAddHost) {
             AddHostSheet { store.add($0) }