Add complexionFormId to appearance payload

Introduce complexionFormId (TXST) into RemoteAppearance and the appearance protocol so complexion textures are captured and serialized. Updates: header/state, Networking JSON parse/serialize, proxy actor comparisons, main capture logic, protocol docs, fake client/player samples, changelog and dev-log. Capture reads PlayerCharacter::complexion and serializes it, but applying to proxies is intentionally a no-op because TESNPC proxies lack a complexion field (documented in comments/dev-log). Files: plugin/include/F4TRemotePlayerState.h, plugin/src/*, protocol/packets.md, server/fake_client.py, server/fake_player.py, changelog.md, docs/dev-log.md.

changelog.md

@@ -10,6 +10,7 @@ For testing notes, milestone summaries, known issues, and next steps, see [`docs
 ## [Unreleased]
 
 ### Added
+- Complexion texture form reference (`complexionFormId`) to appearance payload so hands, arms, and body match the synced skin tone (follows the existing hair colour pattern).
 - Appearance protocol version 3 with an optional `tints` field (character tint layers: skin tone, complexion, makeup, beard shade) so proxies can mirror the sender's skin colour and facial detail.
 - Capture of player/NPC `tintingData` in `CaptureLocalAppearance`, plus game-thread application of tints onto runtime proxies: existing entries are updated in place by template ID, and missing entries are reconstructed against the proxy race's tint templates (skipped when no template resolves).
 - `server/fake_client.py` parsing/output and `server/fake_player.py` sample payload for the new `tints` appearance field.