Add GPT-5.5 Pro/xhigh and Gemini 3.5 Flash runs; fix three artifacts

Surgical fixes (originals preserved in history), each documented in the
per-model run notes as: where the bug is, pre-fix behavior, root cause,
with the shown build being the fixed one:
- grok-build: 0xAETHER invalid hex literal killed the script at parse
  time (pure black screen); atlas flipY mismatch made near terrain
  sample undrawn black texels. 2 lines.
- composer-2-5: horizontal movement multiplied dt twice, walking at
  ~1/60 design speed and making biomes effectively unreachable. 1 line.
- gpt-5-5-pro: 8x2 atlas rows swapped by default flipY, grass became
  obsidian and leaves/sand sampled undrawn slots. 1 line.

Gemini 3.5 Flash added as-is (color/transparency analysis next).

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

outputs/composer-2-5/mythos-craft.html

@@ -1149,7 +1149,7 @@ class Player {
     if (this.keys['KeyS']) move.sub(forward);
     if (this.keys['KeyA']) move.sub(right);
     if (this.keys['KeyD']) move.add(right);
-    if (move.length() > 0) move.normalize().multiplyScalar(speed * dt);
+    if (move.length() > 0) move.normalize().multiplyScalar(speed); // fix: was `speed * dt` — tryMove() multiplies by dt again, so walking ran at speed*dt^2 (~1/60 of design speed)
 
     this.velocity.x = move.x;
     this.velocity.z = move.z;