feat(entitlement): pre-release switch so Release builds can test 60 fps

The frame-rate boundary is correct as a product rule, but it only bites in a
Release build, where DevBuild.IsDevelopment is false and DeveloperMode cannot
unlock anything — exactly the build whose performance numbers are worth reading
(see docs/ai/environment.md: Debug pixel paths are several times slower). 60 fps
could not be tested at all.

OutputProfile.EntitlementEnforced is false: every shipped tier is selectable by
any build, and HasProOutput — the one property the tier setter, the dropdown's
strikethrough and the locked-item style all read — answers yes regardless of
ownership. static readonly rather than const, so the consumed `||` does not fold
into unreachable operand code (same reason as DevBuild.IsDevelopment).

The licence indicator row is suppressed while the switch is off: it exists to
explain what the boundary costs, and claiming "Steam ID Limit: 60fps" to an
unowned build would be a false statement. Docs corrected in place — the enforced
rule is unchanged, only its state is recorded.

Tests: one integration case covers both switch states (unowned build reaches
1080p60 with the switch off, 1080p30 with it on), so flipping at launch leaves no
red test behind. The two suites that anchor on the pinned licence row early-return
while it is absent; EntitlementTests covers that state meanwhile.

667 pass, build 0 warnings.

ytLive.Tests/EntitlementTests.cs

@@ -1,6 +1,8 @@
 using System;
 using System.IO;
+using System.Linq;
 using Xunit;
+using ytLive.Models;
 using ytLive.Services.Entitlement;
 using ytLive.ViewModels;
 
@@ -87,7 +89,12 @@ public class EntitlementTests
 
             vm.EntitlementOverride = new FakeEntitlement(false);
             Assert.False(vm.IsAppOwned);
-            Assert.False(vm.HasProOutput);
+            // Pro output is what the frame-rate boundary answers, and while the pre-release switch is
+            // off that answer is yes regardless of ownership. The rail still moves IsAppOwned itself,
+            // and the paid-limit row is absent because nothing is being limited.
+            Assert.Equal(!OutputProfile.EntitlementEnforced, vm.HasProOutput);
+            Assert.Equal(OutputProfile.EntitlementEnforced,
+                vm.AttentionAlerts.Any(alert => alert.Id == "steam-licence"));
 
             vm.EntitlementOverride = new FakeEntitlement(true);
             Assert.True(vm.IsAppOwned);
@@ -99,4 +106,36 @@ public class EntitlementTests
             try { File.Delete(tempDb); } catch (IOException) { }
         }
     }
+
+    /// <summary>
+    /// The pre-release switch is the only thing that lets an <b>unowned</b> build reach 60 fps, which
+    /// is what makes Release-build performance testing possible before the paid edition ships.
+    ///
+    /// <para>Written against both states of <see cref="OutputProfile.EntitlementEnforced"/> so
+    /// flipping it at launch does not leave a red test behind: with the switch off the unowned view
+    /// model keeps 1080p60; with it on the tier setter refuses it and the free tier stands.</para>
+    /// </summary>
+    [Fact]
+    public void An_unowned_build_reaches_60_fps_only_while_the_gate_is_unenforced()
+    {
+        var tempDb = Path.Combine(Path.GetTempPath(), $"llamacasty-entitlement-{Guid.NewGuid():N}.db");
+        MainViewModel.LayoutPathOverride = tempDb;
+        try
+        {
+            var vm = new MainViewModel { EntitlementOverride = new FakeEntitlement(false) };
+
+            vm.SelectedQuality = vm.QualityOptions.Single(tier => tier.Display == "1080p60");
+
+            Assert.False(vm.IsAppOwned);
+
+            // The tier the encoder would actually be built from (MainViewModel.Streaming.Operations).
+            var landed = OutputProfile.Resolve(vm.SelectedQuality, vm.QualityOptions, vm.HasProOutput);
+            Assert.Equal(OutputProfile.EntitlementEnforced ? 30 : 60, landed.Fps);
+        }
+        finally
+        {
+            MainViewModel.LayoutPathOverride = null;
+            try { File.Delete(tempDb); } catch (IOException) { }
+        }
+    }
 }