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/ch57_B_nop_runway.mem

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+// Ch57 image B — strict-NOP runway (96 words).
+// Same AdES handler at [0x80..0x8C] as Ch54 built-in, but 0x90..0x1FC
+// is all NOPs instead of (JR $31; NOP) pairs.
+// Semantic probe: does the BIOS's progress depend on the "safe return"
+// shape of the runway, or just on the bytes being non-trapping?
+//   words 0..3   = MFC0/ADDIU/JR/RFE (AdES handler)
+//   words 4..95  = 92 x NOP (0x00000000)
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