chore: remove kbx-foundation-v36 reference (superseded by v4 implementation)

Removed entire kbx-foundation-v36 directory as it's been replaced by
the new KBX Foundation v4 patterns implemented in this session:
- Registry-driven screen definitions
- Density-aware UI adapter components
- Feature module templates (ShadowRun, Models)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

docs/Design/kbx-foundation-v52-fe-operational-navigation-screen-anatomy/backend/tests/ExternalData/KbxExternalDataFreshnessPolicyTests.cs

@@ -0,0 +1,28 @@
+using Kbx.Shared.ExternalData;
+using Kbx.Shared.ExternalData.Generated;
+using Xunit;
+namespace Kbx.Tests.ExternalData;
+public sealed class KbxExternalDataFreshnessPolicyTests
+{
+    [Fact] public void Strict_dataset_does_not_allow_stale_fallback()
+    {
+        var d=KbxExternalDataCatalog.All["dataset.kis.domestic-stock.current-price"];
+        var received=new DateTimeOffset(2026,8,8,9,0,0,TimeSpan.Zero);
+        var w=KbxExternalDataFreshnessPolicy.Window(d,received);
+        Assert.Equal(w.FreshUntil,w.UsableUntil);
+        Assert.Equal(KbxExternalDataState.Expired,KbxExternalDataFreshnessPolicy.Evaluate(d,received.AddSeconds(4),w.FreshUntil,w.UsableUntil));
+    }
+    [Fact] public void Stale_while_revalidate_is_explicit()
+    {
+        var d=KbxExternalDataCatalog.All["dataset.opendart.company-profile"];
+        var received=new DateTimeOffset(2026,8,7,8,0,0,TimeSpan.Zero);
+        var w=KbxExternalDataFreshnessPolicy.Window(d,received);
+        Assert.Equal(KbxExternalDataState.Stale,KbxExternalDataFreshnessPolicy.Evaluate(d,received.AddHours(25),w.FreshUntil,w.UsableUntil));
+    }
+    [Fact] public void Krx_generic_dataset_requires_service_policy()
+    {
+        var d=KbxExternalDataCatalog.All["dataset.krx.approved-service"];
+        Assert.Null(d.FreshForSeconds);
+        Assert.Equal("provider-defined",d.FreshnessMode);
+    }
+}