feat: sp_field read-only field-record dumper (resolve field+0x38 layout)

Walks a live entity's serializer field array, dumps the qword window (0x20..0x50)
around a named field with pointer-likeness tags + one-level deref, to settle
whether field+0x38 is the encoder dispatch ptr (Ghidra) or m_nFieldSize/Offset
(earlier gdb read) before implementing the swap. Read-only, range-gated derefs.

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