fix(rendering): restore retail terrain texture tiling

Carry TerrainTex.TexTiling through the terrain atlas and upload a layer-indexed table to the modern bindless shader so base, overlay, and road textures repeat at retail scale. Keep alpha masks cell-scaled and preserve retail's verified source-level-zero high-detail selection.

Add the named-retail pseudocode, WorldBuilder/ACE/ACME cross-reference, adapter conformance tests, and inventory documentation so a future renderer migration keeps the contract.

Co-Authored-By: Codex <noreply@openai.com>

src/AcDream.App/Rendering/TerrainTextureTilingTable.cs

@@ -0,0 +1,40 @@
+namespace AcDream.App.Rendering;
+
+/// <summary>
+/// Builds the layer-indexed adapter table consumed by
+/// <c>terrain_modern.frag</c>. Retail passes <c>TerrainTex::tex_tiling</c>
+/// directly to <c>ImgTex::TileCSI</c> / <c>ImgTex::MergeTexture</c>
+/// (`TexMerge::CopyAndTile` 0x00503580, `TexMerge::Merge` 0x005038C0).
+/// The table is the modern texture-array equivalent of that per-texture
+/// argument.
+/// </summary>
+internal static class TerrainTextureTilingTable
+{
+    // WorldBuilder's extracted terrain-array path uses the same 36-layer
+    // contract. Packed terrain layer indices are validated against this
+    // capacity before the shader table is built.
+    internal const int LayerCapacity = 36;
+
+    internal static float[] Build(IEnumerable<(uint Layer, uint RepeatCount)> entries)
+    {
+        ArgumentNullException.ThrowIfNull(entries);
+
+        var table = new float[LayerCapacity];
+        Array.Fill(table, 1f);
+
+        foreach (var (layer, repeatCount) in entries)
+        {
+            if (layer >= LayerCapacity)
+            {
+                throw new InvalidOperationException(
+                    $"Terrain atlas layer {layer} exceeds the shader capacity of {LayerCapacity} layers.");
+            }
+
+            // Preserve the dat value exactly. Retail forwards the unsigned
+            // field without normalizing it in both CopyAndTile and Merge.
+            table[layer] = repeatCount;
+        }
+
+        return table;
+    }
+}