fix(runtime): align portal and movement presentation

Port retail portal viewport projection and reveal behavior, preserve outbound combat style, drive remote and local grounded movement from authored CSequence root frames, and reuse the local prepared pose so animation hooks advance once.

User-verified portal, observer movement, combat stance, and short-tap locomotion gates. Release build passed with 5,767 tests and five intentional skips.

Co-authored-by: OpenAI Codex <codex@openai.com>

tests/AcDream.App.Tests/Rendering/SkyProjectionTests.cs

@@ -0,0 +1,52 @@
+using System.Numerics;
+using AcDream.App.Rendering.Sky;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class SkyProjectionTests
+{
+    [Theory]
+    [InlineData(60f)]
+    [InlineData(120f)]
+    [InlineData(179.885f)]
+    public void WithDepthRange_PreservesActiveFieldOfView(float degrees)
+    {
+        Matrix4x4 active = Matrix4x4.CreatePerspectiveFieldOfView(
+            degrees * MathF.PI / 180f,
+            16f / 9f,
+            0.1f,
+            5_000f);
+
+        Matrix4x4 sky = SkyProjection.WithDepthRange(active, 0.1f, 1_000_000f);
+
+        Assert.Equal(active.M11, sky.M11);
+        Assert.Equal(active.M22, sky.M22);
+        Assert.Equal(active.M34, sky.M34);
+        Assert.Equal(active.M44, sky.M44);
+        Assert.Equal(1_000_000f / (0.1f - 1_000_000f), sky.M33, precision: 6);
+        Assert.Equal(0.1f * 1_000_000f / (0.1f - 1_000_000f), sky.M43, precision: 6);
+    }
+
+    [Fact]
+    public void WithDepthRange_PreservesOffCenterProjectionTerms()
+    {
+        Matrix4x4 active = Matrix4x4.CreatePerspectiveOffCenter(
+            -0.8f, 1.2f, -0.5f, 0.7f, 0.1f, 5_000f);
+
+        Matrix4x4 sky = SkyProjection.WithDepthRange(active, 1f, 10_000f);
+
+        Assert.Equal(active.M11, sky.M11);
+        Assert.Equal(active.M22, sky.M22);
+        Assert.Equal(active.M31, sky.M31);
+        Assert.Equal(active.M32, sky.M32);
+    }
+
+    [Fact]
+    public void WithDepthRange_RejectsNonPerspectiveProjection()
+    {
+        Matrix4x4 orthographic = Matrix4x4.CreateOrthographic(10f, 10f, 0.1f, 100f);
+
+        Assert.Throws<ArgumentException>(() =>
+            SkyProjection.WithDepthRange(orthographic, 0.1f, 1_000f));
+    }
+}