docs(render): V11 closeout — register, architecture, code structure, issues

Retires the GL framing from the documents that described a two-backend,
two-UI-stack client, and files what the deletion left behind.

Divergence register:
  * AD-46 (anisotropic tap pattern in dense alpha scenery) is REFRAMED rather
    than retired. Its substance survives -- distant foliage may read denser
    than retail's -- but it was measured GL-vs-Vulkan, and with GL gone it is
    a Vulkan-vs-retail question against the D3D oracle it already cited. The
    measurement is kept as the evidence that the residual is a driver tap
    pattern; the row now records that it is no longer falsifiable by
    self-differential, which is a real loss the deletion causes.
  * AD-47 and AD-48 are NEW, and the campaign's own risk register scheduled
    them here: MSAA sample positions (measured at 8.83% of the frame at 4x,
    which is why every strict gate runs MSAA off -- and therefore why a
    regression confined to the multisample path would not be caught) and
    present pacing (#235 is the live instance).
  * AD-17's justification moves from a GL clip-plane citation to Vulkan's
    maxClipDistances floor, which is the same 8, so the divergence is
    unchanged and only its authority moves.
  * AP-92 keeps IUiViewportRenderer.TextureIsBottomUp rather than folding it
    flat, because it is what let the origin question be answered by data.

Architecture and code structure: the layer diagram, the frame order, the
residency vocabulary and the reference table all said OpenGL. The UI section
said two stacks. Rule 3's rationale is rewritten around what actually
happened -- ImGui was deleted and not one panel, ViewModel or command had to
change, because none of them had ever imported ImGuiNET. That is the rule
paying for itself, so it is recorded as evidence rather than removed as
obsolete.

Issues: #258 files the dev-panel host as a decision rather than an accident,
and #255 is REOPENED. Its TaskCreationOptions.LongRunning fix asks the
scheduler for a thread but does not promise two callbacks overlap; under nine
concurrent test assemblies it still failed 2 of 5 whole-suite runs. The
earlier evidence tested a narrower pool, not a contended one. The fix it
needs is a rendezvous inside the read stub -- not a weakened assertion.

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

src/AcDream.App/Rendering/Gpu/GpuBindingModel.cs

@@ -111,7 +111,7 @@ internal static class GpuBindingModel
 
     // ---- set 2: the global texture table ----
 
-    /// <summary>Set index of the sampled-texture descriptor array (Vulkan) / logical table (GL).</summary>
+    /// <summary>Set index of the sampled-texture descriptor array.</summary>
     public const uint TextureTableSet = 2;
 
     /// <summary>Binding of the descriptor array within <see cref="TextureTableSet"/>.</summary>