refactor(camera): extract the update frame

Move fly/chase publication, combat target tracking, and local player projection behind typed runtime owners. Preserve the inbound-created projection/reconcile barrier while removing GameWindow callbacks and duplicate shadow helpers.

src/AcDream.App/Combat/CombatCameraTargetSource.cs

@@ -0,0 +1,53 @@
+using System.Numerics;
+using AcDream.App.Interaction;
+using AcDream.Core.Combat;
+using AcDream.Core.Selection;
+
+namespace AcDream.App.Combat;
+
+internal interface ICombatCameraTargetSource
+{
+    Vector3? GetTrackedTargetPoint();
+}
+
+/// <summary>
+/// Resolves retail's combat-camera target from canonical combat, selection,
+/// gameplay-option, and world-selection owners.
+/// </summary>
+/// <remarks>
+/// <c>ClientCombatSystem::UpdateTargetTracking @ 0x0056A950</c> enables
+/// <c>CameraSet::TrackTarget</c> only for melee/missile combat with the option
+/// enabled and a valid attack target. TrackTarget applies target-local offset
+/// (0, 0, 0.5).
+/// </remarks>
+internal sealed class CombatCameraTargetSource : ICombatCameraTargetSource
+{
+    private readonly ICombatGameplaySettingsSource _settings;
+    private readonly CombatState _combat;
+    private readonly SelectionState _selection;
+    private readonly IWorldSelectionQuery _world;
+
+    public CombatCameraTargetSource(
+        ICombatGameplaySettingsSource settings,
+        CombatState combat,
+        SelectionState selection,
+        IWorldSelectionQuery world)
+    {
+        _settings = settings ?? throw new ArgumentNullException(nameof(settings));
+        _combat = combat ?? throw new ArgumentNullException(nameof(combat));
+        _selection = selection ?? throw new ArgumentNullException(nameof(selection));
+        _world = world ?? throw new ArgumentNullException(nameof(world));
+    }
+
+    public Vector3? GetTrackedTargetPoint()
+    {
+        if (!_settings.ViewCombatTarget
+            || !CombatInputPlanner.SupportsTargetedAttack(_combat.CurrentMode)
+            || _selection.SelectedObjectId is not uint selected)
+        {
+            return null;
+        }
+
+        return _world.GetCombatCameraTargetPoint(selected);
+    }
+}