Add appearance sync and late-join replay

Adds optional `appearance` snapshots to transform packets, applies supported appearance data to runtime proxies, and has the server replay stored transforms to newly connected clients so late joiners receive current visuals immediately.

protocol/player-sync.md

@@ -18,6 +18,12 @@ local movement logs: while the player is moving, the plugin targets roughly
 server assigns a `playerId`, adds `serverTime`, and broadcasts transform packets
 to other connected clients.
 
+When a new client connects, the server sends the last stored transform snapshot
+for each already-connected player to that new client after `welcome`. These
+snapshots include optional fields such as `equippedItems` and `appearance`, so a
+late joiner can initialize proxy visuals before the existing players' next idle
+heartbeat or movement packet.
+
 The Fallout 4 plugin also receives server packets on a background networking
 thread. It stores its assigned `playerId`, stores remote transform state by
 remote `playerId`, and removes remote state when disconnect packets arrive.
@@ -64,6 +70,7 @@ weaponDrawn
 movementSpeed
 animationGraphSpeed
 equippedItems
+appearance
 lastReceivedLocalTime
 ```
 
@@ -79,6 +86,13 @@ tracked visible apparel slots with `{ slot, formId }` entries; empty `formId`
 values mean that tracked slot is intentionally unequipped. Older clients can
 omit the field and receivers keep the proxy's existing/default appearance.
 
+`appearance` is optional and versioned. It carries male-proxy-compatible body
+and face data such as race form ID for diagnostics/future use, height, body
+morph weight, body tint color, hair color, facial hair color, head-part form IDs,
+and morph slider values. Receivers apply supported fields only after proxy 3D is
+loaded. Gender switching is intentionally omitted until female proxy support is
+available.
+
 This model proves the data shape and lifecycle before spawning remote actors.
 For the current visual milestone, the controller represents only one remote
 player and chooses the lowest available `playerId` if more than one remote
@@ -115,6 +129,9 @@ player exists.
 - Transform packets can include optional `equippedItems` snapshots for visible
   clothing, armor, hats, and eyewear slots. The game-thread proxy controller
   applies those snapshots after proxy 3D is loaded.
+- Transform packets can include optional `appearance` snapshots for best-effort
+  body and face proxy visuals. The game-thread proxy controller applies supported
+  fields after proxy 3D is loaded and defers race/gender switching.
 - The plugin suppresses transform sends and proxy representation in the
   `COVault109` solo cell.
 - The game-thread proxy controller applies confirmed Havok animation graph