tooling: vendor nosoop makesig + headless Java port; adopt canonical 21-byte EncodeField sig

Ran the makesig algorithm on EncodeField (Ghidra 0x4334e0 = file 0x3334e0 +
0x100000 image base): shortest-unique sig = 21 bytes, no wildcards (prologue
has no ADDRESS/DYNAMIC operands), the unique prefix of the hand-extracted bytes.
Adopted it in gamedata + module const. Added tools/ (makesig.py vendored w/
attribution, GhidraEncodeFieldSig.java headless port, README) and RE doc §8 note.

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