feat(runtime): define borrowed views commands and ordered events

Establish the J1 presentation-independent contract with instance-scoped clocks and generations, immutable borrowed views, typed generation-gated commands, normalized ordered diagnostics, and teardown acknowledgements. Route graphical startup plus press-time selection, movement, and combat through focused App adapters over the exact existing owners without adding a queue or mirrored world.

Validated by the Release solution build, 13 Runtime tests, 3,838 App tests with three existing skips, and the complete 8,424-test Release suite with five existing skips.

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

src/AcDream.App/Update/UpdateFrameOrchestrator.cs

@@ -1,6 +1,7 @@
 namespace AcDream.App.Update;
 
 using AcDream.App.Streaming;
+using AcDream.Runtime;
 
 /// <summary>
 /// The host-supplied input for one update callback.
@@ -26,29 +27,31 @@ internal readonly record struct UpdateFrameTiming(
 /// hooks, and the later script drain. Absolute liveness time and raw-mouse
 /// idle time intentionally do not enter this clock.
 /// </remarks>
-internal sealed class UpdateFrameClock : IPhysicsScriptTimeSource
+internal sealed class UpdateFrameClock
+    : IPhysicsScriptTimeSource,
+      IGameRuntimeClock
 {
-    public double CurrentScriptTime { get; private set; }
+    private readonly GameRuntimeClock _runtime = new();
+
+    public ulong FrameNumber => _runtime.FrameNumber;
+    public double SimulationTimeSeconds => _runtime.SimulationTimeSeconds;
+    public double CurrentScriptTime => _runtime.SimulationTimeSeconds;
 
     public UpdateFrameTiming Advance(
         UpdateFrameInput input,
         bool advanceScriptClock = true)
     {
-        double deltaSeconds = NormalizeDeltaSeconds(input.HostDeltaSeconds);
-        if (advanceScriptClock)
-            CurrentScriptTime += deltaSeconds;
+        RuntimeFrameTime frame = _runtime.Advance(
+            input.HostDeltaSeconds,
+            advanceScriptClock);
         return new UpdateFrameTiming(
-            deltaSeconds,
-            (float)deltaSeconds,
-            CurrentScriptTime);
+            frame.DeltaSeconds,
+            (float)frame.DeltaSeconds,
+            frame.SimulationTimeSeconds);
     }
 
     public static double NormalizeDeltaSeconds(double deltaSeconds) =>
-        double.IsFinite(deltaSeconds)
-        && deltaSeconds > 0.0
-        && deltaSeconds <= float.MaxValue
-            ? deltaSeconds
-            : 0.0;
+        GameRuntimeClock.NormalizeDeltaSeconds(deltaSeconds);
 }
 
 internal interface IPhysicsScriptTimeSource