Add engine-debug-tools and fix critter animation rendering bugs

- engine-debug-tools/: a debug dump hotkey + dump2png to inspect
  decoded critter frames independent of the renderer (see root
  README.md's "Debugging" section).
- engine-patches/04,05: fix critter sprite scale and an OpenGL
  texture cache collision, found using that tooling.
- mdlp: fix encodeFrames RLE-diffing upscaled frames against a
  previous-frame reference the real RSD8 decoder never implements
  (verified against Night Dive's original Mac source down to the
  68K assembly) - was rendering as scattered static in-game.
- Upscale pipeline: better color quantization (dithering, pure-ramp
  exclusion) and per-resource model selection.

run-image.sh

@@ -43,13 +43,17 @@ TTY_FLAGS="-i"
 # build-image/prepare-android-project.sh --host-paths) write paths that
 # resolve on the HOST filesystem instead of this container's own
 # /workspace - needed so a gradlew/Android Studio running natively on the
-# host afterwards can find them.
+# host afterwards can find them. ENGINE_DEBUG_TOOLS: forwarded so the
+# Makefile's dist_debug target can tell build-engine.sh to also apply
+# engine-debug-tools/engine-patches/ (see root README.md's "Debugging"
+# section) - empty/unset for every normal build.
 # shellcheck disable=SC2086
 docker run --rm $TTY_FLAGS \
     -v "$ROOT:/workspace" \
     -e HOST_UID="$(id -u)" \
     -e HOST_GID="$(id -g)" \
     -e HOST_REPO_ROOT="$ROOT" \
+    -e ENGINE_DEBUG_TOOLS="${ENGINE_DEBUG_TOOLS:-}" \
     "$IMAGE" \
     "$@"