docs: proxy animation investigation conclusive - animations not feasible

Investigation summary:
- Tested velocity-based animation triggering: graph variable writes, animation
  events, character controller velocity manipulation, and Move() API calls
- All approaches failed: animations do not play on SetPosition-backed proxy actors
- Root cause: Fallout 4's animation system requires active AIProcess-driven
  locomotion packages, which are incompatible with networked puppet actors
- Fallout 4's animation system fundamentally ties animation evaluation to the
  character controller's actual velocity AND active AI-driven locomotion state
- PlaceAtMe proxies updated via SetPosition cannot provide either requirement

Proxy actors currently work correctly for:
- Smooth position synchronization
- Heading/rotation updates
- Jump animations (via Z-position)
- Network sync and lifecycle

What remains impossible without deep engine access:
- Walk/run/sneak animation playback
- Animation graph variable manipulation affecting behavior
- Character controller velocity synthesis for puppets

Recommendation: Accept this architectural limitation and provide alternative
visual feedback (particles, glows, state indicators) instead of animations.

Files changed:
- plugin/src/F4TProxyActorController.cpp: Reverted to SetPosition-only approach
- docs/dev-log.md: Added comprehensive investigation summary and conclusions

Co-authored-by: Cursor <cursoragent@cursor.com>

protocol/player-sync.md

@@ -96,8 +96,11 @@ player exists.
   position when the represented player disconnects, disappears, or leaves the
   local test cell, then snaps back to a valid same-cell remote player before
   resuming smoothing.
-- Transform packets now include basic movement state data for future animation
-  work, but the proxy actor does not apply animations from that state yet.
+- Transform packets include movement state data (`isMoving`, `movementSpeed`,
+  `isSprinting`, `isSneaking`, `isJumping`, `weaponDrawn`).
+- The game-thread proxy controller applies confirmed Havok animation graph
+  variables to runtime proxy actors from that remote state (locomotion, sneak,
+  jump, weapon drawn). Transform position/heading sync is unchanged.
 
 ## Transform Cadence
 
@@ -114,8 +117,9 @@ normal send interval and are sent immediately. The receiving plugin still stores
 remote transform state on the networking thread and moves actors only from the
 game-thread proxy controller.
 
-No Fallout 4 remote actor is dynamically spawned yet.
-No animation graph sync or animation application is implemented yet.
+Runtime proxy actors are spawned per remote `playerId` in the test cell (see
+architecture). Full animation graph replication is not implemented; only curated
+graph variable writes drive proxy locomotion visuals.
 
 ## Planned Later