feat(physics): Campaign P P1 - stat-coupled movement (burden/stamina/vitae)

Ports the retail CACQualities/EncumbranceSystem/MovementSystem chain
(named-retail decomp pc 256393/412901-414050/416169-416320/695958+) so
PlayerWeenie's run rate, jump height, jump permission, and jump stamina
cost are real functions of burden, current stamina, and vitae/skill
enchantments instead of stubs.

Core:
- New EncumbranceSystem.cs (delegates to the already-verified
  BurdenMath formulas — one source of truth for the burden HUD and
  movement physics) and MovementSystem.cs (GetRunRate/GetJumpHeight/
  JumpStaminaCost/GetJumpPower, decomp-cited; ACE cross-referenced
  where BN dropped the general-case arithmetic entirely).
- PlayerWeenie rewritten as the CACQualities-shaped composition:
  CanJump gates on burden (<2.0 load, UN-8 — x87 polarity resolved by
  plausibility, Ghidra MCP unavailable this slice), JumpStaminaCost
  returns the real ceil((load+0.5)*power*8+2) cost and always affords
  it (matches decomp — retail's own function never refuses; "weak"
  jump comes entirely from the stamina==0 skill-zeroing gate inside
  InqRunRate/InqJumpVelocity, not a hard refusal), SetStamina wires a
  null="unknown, don't gate" sentinel preserving every pre-P1 test.
- EnchantmentMath.GetMod gained an optional StatModType flag filter
  (GetSkillMod convenience wrapper) so the SAME vitae/family-stacking
  machinery already used for vital-max buffs now also answers "what's
  the vitae+skill-enchantment-adjusted Run/Jump skill" — reusing the
  M3 active-enchantment state, not a new engine.

Runtime:
- RuntimeCharacterState now stores the pre-EnchantSkill base run/jump
  skill and recomputes the adjusted value (vitae first, then matching
  Skill-flagged buffs, floor 0.5, truncate) on every base push AND on
  every Spellbook.EnchantmentsChanged notification — a vitae change
  alone moves the produced rate without a fresh PlayerDescription.
- RuntimeMovementSkillState extended with Burden/CurrentStamina
  (RuntimeMovementSkillProjection.ApplyTo pushes both through the
  existing seam); LiveSessionEventRouter recomputes burden from the
  same Strength+aug-property+EncumbranceVal inputs the burden HUD
  already assembles (reacting to the same ClientObjectTable events)
  and pushes current stamina from LocalPlayerState vital updates.
- Wires the previously dead-lettered ReportExhaustion() R3-W4 seam:
  LiveSessionRuntimeFactory's OnMovementStatsUpdated callback re-
  applies the current snapshot to the live controller and forces an
  immediate movement re-evaluation on any skill/burden/stamina change.

Register: retires TS-5 (CanJump/JumpStaminaCost stubs) and AP-25 (no
vitae in pushed skill). Adds AP-127 (two minor unmodeled retail bonus
properties + the stamina-buff-adjusts-local-copy nuance, deliberately
out of the bounded "run/jump query path only" scope) and UN-8 (the
CanJump x87 polarity call, flagged for a future Ghidra MCP
confirmation pass). Extends TS-23 (PlayerKillerStatus not parsed) to
cover JumpStaminaCost's new pk parameter, hardcoded false pending P3.

Full pseudocode + retail citations + the vitae/skill-level finding in
docs/research/2026-07-30-stat-coupled-movement-pseudocode.md.

Release suite: Core.Tests 3977/2 skips, Runtime.Tests 425/0 skips,
App.Tests 3968/3 skips — all green. (One pre-existing, unrelated Debug-
only flake in LandblockBuildOriginTests reproduces on the pre-P1
baseline and passes in Release; not touched here.)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.Core/Physics/EncumbranceSystem.cs

@@ -0,0 +1,43 @@
+namespace AcDream.Core.Physics;
+
+/// <summary>
+/// Retail <c>EncumbranceSystem</c> (named-retail decomp
+/// <c>docs/research/named-retail/acclient_2013_pseudo_c.txt</c> pc 256393),
+/// the pure load/capacity math consumed by <see cref="MovementSystem"/> and
+/// <see cref="PlayerWeenie"/>'s <c>InqLoad</c>-equivalent chain.
+///
+/// <para>
+/// These are the SAME three formulas <c>AcDream.Core.Items.BurdenMath</c>
+/// already ports (verified against the identical retail addresses, used by
+/// the burden HUD / character sheet / indicator bar). Rather than re-derive
+/// them a second time under a different name, this class delegates —
+/// P1 (2026-07-30, Campaign P) needs the retail-named surface next to
+/// <see cref="MovementSystem"/> for citation clarity, but a single formula
+/// implementation keeps the burden HUD and movement physics from drifting
+/// apart. See <c>docs/research/2026-07-30-stat-coupled-movement-pseudocode.md</c>
+/// §2 and §6.
+/// </para>
+/// </summary>
+public static class EncumbranceSystem
+{
+    /// <summary>
+    /// <c>EncumbranceSystem::EncumbranceCapacity</c> 0x004fcc00:
+    /// <c>strength &lt;= 0 ? 0 : strength*150 + clamp(aug*30, 0, 150)*strength</c>.
+    /// </summary>
+    public static int EncumbranceCapacity(int strength, int aug) =>
+        AcDream.Core.Items.BurdenMath.EncumbranceCapacity(strength, aug);
+
+    /// <summary>
+    /// <c>EncumbranceSystem::Load</c> 0x004fcc40: <c>burden / capacity</c>
+    /// (1.0 = at capacity). Returns 0 when capacity &lt;= 0 (no-data).
+    /// </summary>
+    public static float Load(int capacity, int burden) =>
+        AcDream.Core.Items.BurdenMath.LoadRatio(capacity, burden);
+
+    /// <summary>
+    /// <c>EncumbranceSystem::LoadMod</c> 0x004fcc70: full effectiveness
+    /// through 100% load, linear falloff to zero at 200%, zero above it.
+    /// </summary>
+    public static float LoadMod(float load) =>
+        AcDream.Core.Items.BurdenMath.LoadModifier(load);
+}