docs(gamedata): clean rewrite — 9 entries, Phase1/Phase2 grouped, descriptive comments

Replaces the append-with-leading-commas mess; same 9 verified sigs (EncodeField,
EncodeInt32, SendClientMessages, PerClientEncode, WriteDeltaEntity_Internal,
WriteFieldList, GetBitRange, BitCopyPrimitive, VarintWriter) with RVAs + roles
documented. Matches what's deployed.

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