Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

RTL (GS rasterizer, EE core stub, platform bridge, LPDDR4B path), sim regression
(272 TBs), docs, and tooling. Copyrighted PS2 content (BIOS, game code, GS dumps,
and all dump-derived textures/traces) is excluded via .gitignore and stays local.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sim/data/top_psmct32_raster_demo/.gitignore

@@ -0,0 +1,10 @@
+# Ch343 — the authentic-cube board fixtures are DERIVED from the cubes .gs dump
+# (downscaled texture + perspective geometry) and therefore carry copyrighted game
+# content. Per captures/gs/.gitignore policy, NEVER commit dump-derived material.
+# These are regenerated locally from the extracted dump with:
+#     python3 tools/gs_make_cube_fixture.py
+# Everything else in this dir (hand-authored synthetic fixtures) stays committed.
+payload_cube_setup.mem
+bios_cube_setup.mem
+feeder_cube_persp.mem
+feeder_cube_tex.mem