docs: full reverse-engineering writeup (docs/REVERSE_ENGINEERING.md)

Consolidates ALL the CS2 RE: Source1-vs-Source2 networking, the EncodeField +0x38 hook
point + signature, the game-function resolution (entity vtable[0] GetNetworkSerializerInfo
-> CNetworkSerializerClassInfo -> FindField), CNetworkSerializerFieldInfo/ClassInfo layouts,
the per-client send loop (SendClientMessages/WriteDeltaEntity) + per-client verdict, the
recipients filter, ModSharp resolution tooling (verified), dead ends, and an offsets table.
Linked from README.

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