fix(rendering): bound portal resource lifetime

Separate logical ownership, render publication, and GPU retirement across live entities, landblocks, particles, textures, mesh arenas, portal/UI teardown, and per-frame scratch storage. Add bounded DAT/texture caches, upload budgets, three-frame fence retirement, exact-incarnation appearance reconciliation, frame pacing, and extensive lifetime conformance coverage.\n\nThe seven-destination connected route now cuts peak working/private memory roughly in half, returns Caul to 125-153 FPS locally, and produces no WER or AMD reset.\n\nCo-authored-by: OpenAI Codex <codex@openai.com>

src/AcDream.App/Rendering/FramePacingPolicy.cs

@@ -0,0 +1,31 @@
+namespace AcDream.App.Rendering;
+
+/// <summary>
+/// Resolves the user's presentation preference into a bounded render policy.
+/// A normal client is never uncapped: disabling VSync selects a software
+/// ceiling at the active monitor's refresh rate. Only the explicit startup
+/// diagnostic may disable both mechanisms.
+/// </summary>
+internal readonly record struct FramePacingPolicy(
+    bool UseVSync,
+    double? SoftwareLimitHz)
+{
+    internal const double FallbackRefreshHz = 60d;
+
+    public static FramePacingPolicy Resolve(
+        bool requestedVSync,
+        bool uncappedRendering,
+        int? monitorRefreshHz)
+    {
+        if (uncappedRendering)
+            return new FramePacingPolicy(UseVSync: false, SoftwareLimitHz: null);
+
+        if (requestedVSync)
+            return new FramePacingPolicy(UseVSync: true, SoftwareLimitHz: null);
+
+        double refreshHz = monitorRefreshHz is > 0
+            ? monitorRefreshHz.Value
+            : FallbackRefreshHz;
+        return new FramePacingPolicy(UseVSync: false, SoftwareLimitHz: refreshHz);
+    }
+}