ADR-0001 Rev 2: 51-bit PhysAddr layout with concrete sub-unit tables

Remove rack_id (4 bits), rename sip_seg→die_id, shift fields to enable
42-bit local_offset (4 TB per die). Define PE_LOCAL/MCPU_LOCAL/CUBE_SRAM
sub-unit tables for AHBM dies and IOCPU sub-unit table for IOCHIPLET
dies (1 TB window). Supersedes ADR-0031.

Also fixes latent VA/PA confusion in pe_dma pipeline DMA path where
virtual addresses were decoded as physical addresses without MMU
translation — previously masked by coincidental bit-position alignment.

529 passed (+6 recovered), 10 pre-existing failures unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test_engine.py

@@ -29,7 +29,7 @@ def _hbm_pa(sip: int = 0, cube: int = 0, pe_id: int = 0) -> int:
     # 48 GB / 8 slices = 6 GB per slice
     slice_bytes = 48 * (1 << 30) // 8
     pa = PhysAddr.pe_hbm_addr(
-        rack_id=0, sip_id=sip, cube_id=cube, pe_id=pe_id,
+        sip_id=sip, die_id=cube, pe_id=pe_id,
         pe_local_hbm_offset=0x1000, slice_size_bytes=slice_bytes,
     )
     return pa.encode()
@@ -37,7 +37,7 @@ def _hbm_pa(sip: int = 0, cube: int = 0, pe_id: int = 0) -> int:
 
 def _sram_pa(sip: int = 0, cube: int = 0) -> int:
     """Create an SRAM physical address."""
-    pa = PhysAddr.cube_sram_addr(rack_id=0, sip_id=sip, cube_id=cube, sram_offset=0x800)
+    pa = PhysAddr.cube_sram_addr(sip_id=sip, die_id=cube, sram_offset=0x800)
     return pa.encode()