feat(entitlement): pivot to paid app ownership

Check Steam ownership of the paid app with BIsSubscribedApp; keep Debug fake ownership out of Release. Ref: https://partner.steamgames.com/doc/api/ISteamApps#BIsSubscribedApp

ytLive.Tests/EntitlementTests.cs

@@ -7,12 +7,10 @@ using ytLive.ViewModels;
 namespace ytLive.Tests;
 
 /// <summary>
-/// The entitlement seam (2026-11-01): one question — "may this session emit Pro output?" — with a
-/// Steam DLC rail, a Polar rail to come, and a fail-closed default.
+/// Steam ownership is cached once into the app-wide binary flag.
 ///
-/// <para>The rule that must never break: **no configured rail means the free profile**. A missing
-/// DLC id, a missing Steam client or a thrown native load all resolve to false; none of them may
-/// crash the app or quietly grant Pro.</para>
+/// <para>The rule that must never break: a missing paid app ID, Steam client, or native library
+/// fails closed.</para>
 /// </summary>
 // Shares the static MainViewModel.LayoutPathOverride with the sibling class; without a
 // shared collection xUnit runs them in parallel and the two view models fight over one temp DB.
@@ -20,27 +18,44 @@ namespace ytLive.Tests;
 public class EntitlementTests
 {
     [Fact]
-    public void No_configured_dlc_id_reads_as_no_entitlement()
+    public void No_configured_paid_app_id_reads_as_not_owned()
     {
-        // The state before the Steamworks app exists: pure false, no native call attempted.
-        Assert.False(SteamEntitlement.NotConfigured().IsPro);
+        Assert.False(SteamEntitlement.NotConfigured().IsAppOwned);
     }
 
     [Fact]
-    public void A_steam_entitlement_without_a_client_is_the_free_tier_not_a_crash()
+    public void Steam_ownership_checks_the_paid_app_id()
     {
-        // No steam_appid.txt in the test host and no client running: Init fails, we report false.
-        var entitlement = new SteamEntitlement(1234567u);
-        Assert.False(entitlement.IsPro);
+        const uint paidAppId = 1234567u;
+        uint queriedAppId = 0;
+        var entitlement = new SteamEntitlement(
+            paidAppId,
+            initializeSteam: () => true,
+            isAppSubscribed: appId =>
+            {
+                queriedAppId = appId;
+                return true;
+            },
+            shutdownSteam: () => { });
+
+        Assert.True(entitlement.IsAppOwned);
+        Assert.Equal(paidAppId, queriedAppId);
+    }
+
+    [Fact]
+    public void A_steam_entitlement_without_a_client_fails_closed()
+    {
+        var entitlement = new SteamEntitlement(1234567u, () => false, _ => true, () => { });
+        Assert.False(entitlement.IsAppOwned);
     }
 
     [Fact]
     public void The_fake_reports_what_a_test_sets()
     {
         var fake = new FakeEntitlement(true);
-        Assert.True(fake.IsPro);
-        fake.IsPro = false;
-        Assert.False(fake.IsPro);
+        Assert.True(fake.IsAppOwned);
+        fake.IsAppOwned = false;
+        Assert.False(fake.IsAppOwned);
     }
 
     [Fact]
@@ -52,14 +67,16 @@ public class EntitlementTests
         {
             var vm = new MainViewModel();
 
-            // Default rail is NotConfigured → free output.
-            Assert.False(vm.HasProOutput);
-
-            vm.EntitlementOverride = new FakeEntitlement(true);
+            Assert.True(vm.IsAppOwned);
             Assert.True(vm.HasProOutput);
 
             vm.EntitlementOverride = new FakeEntitlement(false);
+            Assert.False(vm.IsAppOwned);
             Assert.False(vm.HasProOutput);
+
+            vm.EntitlementOverride = new FakeEntitlement(true);
+            Assert.True(vm.IsAppOwned);
+            Assert.True(vm.HasProOutput);
         }
         finally
         {