refactor(runtime): own canonical action state

Move selection, combat, and interaction target mode under one Runtime owner; make plugins, retained UI, session routing, and typed runtime views borrow its exact children; and add failure-safe reset, instance isolation, source ownership, and normalized checkpoint coverage without changing retail ordering.

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

src/AcDream.Runtime/GameRuntimeActionViews.cs

@@ -0,0 +1,23 @@
+using AcDream.Core.Combat;
+using AcDream.Runtime.Gameplay;
+
+namespace AcDream.Runtime;
+
+public readonly record struct RuntimeActionSnapshot(
+    long SelectionRevision,
+    uint SelectedObjectId,
+    uint PreviousObjectId,
+    uint PreviousValidObjectId,
+    long CombatRevision,
+    CombatMode CombatMode,
+    int TrackedTargetHealthCount,
+    long InteractionRevision,
+    InteractionModeKind InteractionMode,
+    uint InteractionSourceObjectId);
+
+public interface IRuntimeActionView
+{
+    RuntimeActionSnapshot Snapshot { get; }
+
+    bool TryGetHealth(uint objectId, out float healthPercent);
+}