feat(physics): PlayerWeenie with retail Run/Jump formulas

Implements IWeenieObject with GetRunRate and GetJumpHeight from
decompiled client, cross-referenced against ACE MovementSystem.
Default skills (Run=200, Jump=100) used until skill parsing ships.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/AcDream.Core.Tests/Physics/PlayerWeenieTests.cs

@@ -0,0 +1,84 @@
+using AcDream.Core.Physics;
+using Xunit;
+
+namespace AcDream.Core.Tests.Physics;
+
+public class PlayerWeenieTests
+{
+    [Fact]
+    public void InqRunRate_Skill200_ReturnsCorrectRate()
+    {
+        var pw = new PlayerWeenie(runSkill: 200, jumpSkill: 100);
+        Assert.True(pw.InqRunRate(out float rate));
+        Assert.Equal(2.375f, rate, precision: 3);
+    }
+
+    [Fact]
+    public void InqRunRate_Skill800_ReturnsCap()
+    {
+        var pw = new PlayerWeenie(runSkill: 800, jumpSkill: 100);
+        Assert.True(pw.InqRunRate(out float rate));
+        Assert.Equal(4.5f, rate, precision: 3);
+    }
+
+    [Fact]
+    public void InqRunRate_Skill0_ReturnsBase()
+    {
+        var pw = new PlayerWeenie(runSkill: 0, jumpSkill: 100);
+        Assert.True(pw.InqRunRate(out float rate));
+        Assert.Equal(1.0f, rate, precision: 3);
+    }
+
+    [Fact]
+    public void InqJumpVelocity_FullExtent_Skill100()
+    {
+        var pw = new PlayerWeenie(runSkill: 100, jumpSkill: 100);
+        Assert.True(pw.InqJumpVelocity(1.0f, out float vz));
+        // height = (100/1400) * 22.2 + 0.05 ≈ 1.636
+        // vz = sqrt(1.636 * 19.6) ≈ 5.663
+        Assert.Equal(5.663f, vz, precision: 1);
+    }
+
+    [Fact]
+    public void InqJumpVelocity_HalfExtent_Skill100()
+    {
+        var pw = new PlayerWeenie(runSkill: 100, jumpSkill: 100);
+        Assert.True(pw.InqJumpVelocity(0.5f, out float vz));
+        // height = (100/1400) * 22.2 * 0.5 + 0.05 ≈ 0.843
+        float expectedHeight = 1.0f * (100f / 1400f * 22.2f + 0.05f) * 0.5f;
+        float expectedVz = MathF.Sqrt(expectedHeight * 19.6f);
+        Assert.Equal(expectedVz, vz, precision: 2);
+    }
+
+    [Fact]
+    public void InqJumpVelocity_ZeroSkill_ClampsToMinHeight()
+    {
+        var pw = new PlayerWeenie(runSkill: 0, jumpSkill: 0);
+        Assert.True(pw.InqJumpVelocity(1.0f, out float vz));
+        // height = max(0.05 * 1.0, 0.35) = 0.35
+        // vz = sqrt(0.35 * 19.6) ≈ 2.619
+        Assert.Equal(MathF.Sqrt(0.35f * 19.6f), vz, precision: 2);
+    }
+
+    [Fact]
+    public void GetBurdenMod_Unencumbered_Returns1()
+    {
+        Assert.Equal(1.0f, PlayerWeenie.GetBurdenMod(0f));
+        Assert.Equal(1.0f, PlayerWeenie.GetBurdenMod(0.5f));
+        Assert.Equal(1.0f, PlayerWeenie.GetBurdenMod(0.99f));
+    }
+
+    [Fact]
+    public void GetBurdenMod_Overloaded_Returns0()
+    {
+        Assert.Equal(0.0f, PlayerWeenie.GetBurdenMod(2.0f));
+        Assert.Equal(0.0f, PlayerWeenie.GetBurdenMod(3.0f));
+    }
+
+    [Fact]
+    public void GetBurdenMod_PartialBurden_LinearDecrease()
+    {
+        Assert.Equal(0.5f, PlayerWeenie.GetBurdenMod(1.5f), precision: 3);
+        Assert.Equal(0.75f, PlayerWeenie.GetBurdenMod(1.25f), precision: 3);
+    }
+}