fix: stand-up-on-move and nameplate position tracking

Camera controller / sitting:
- Any movement key (WASD/QE/Space) pressed while sitting now clears the
  sitting flag immediately, matching WoW's sit-to-stand-on-move behaviour
- Added StandUpCallback: when the player stands up via local input the
  callback fires setStandState(0) → CMSG_STAND_STATE_CHANGE(STAND) so
  the server releases the sit lock and restores normal movement
- Fixes character getting stuck in sit state after accidentally
  right-clicking a chair GO in Goldshire Inn (or similar)

Nameplates:
- Use getRenderPositionForGuid() (renderer visual position) as primary
  source for nameplate anchor, falling back to entity X/Y/Z only when
  no render instance exists yet; keeps health bars in sync with the
  rendered model instead of the parallel entity interpolator

src/rendering/camera_controller.cpp

@@ -369,6 +369,7 @@ void CameraController::update(float deltaTime) {
 
     // Toggle sit/crouch with X key (edge-triggered) — only when UI doesn't want keyboard
     // Blocked while mounted
+    bool prevSitting = sitting;
     bool xDown = !uiWantsKeyboard && input.isKeyPressed(SDL_SCANCODE_X);
     if (xDown && !xKeyWasDown && !mounted_) {
         sitting = !sitting;
@@ -376,6 +377,21 @@ void CameraController::update(float deltaTime) {
     if (mounted_) sitting = false;
     xKeyWasDown = xDown;
 
+    // Stand up on any movement key or jump while sitting (WoW behaviour)
+    if (!uiWantsKeyboard && sitting && !movementSuppressed) {
+        bool anyMoveKey =
+            input.isKeyPressed(SDL_SCANCODE_W) || input.isKeyPressed(SDL_SCANCODE_S) ||
+            input.isKeyPressed(SDL_SCANCODE_A) || input.isKeyPressed(SDL_SCANCODE_D) ||
+            input.isKeyPressed(SDL_SCANCODE_Q) || input.isKeyPressed(SDL_SCANCODE_E) ||
+            input.isKeyPressed(SDL_SCANCODE_SPACE);
+        if (anyMoveKey) sitting = false;
+    }
+
+    // Notify server when the player stands up via local input
+    if (prevSitting && !sitting && standUpCallback_) {
+        standUpCallback_();
+    }
+
     // Update eye height based on crouch state (smooth transition)
     float targetEyeHeight = sitting ? CROUCH_EYE_HEIGHT : STAND_EYE_HEIGHT;
     float heightLerpSpeed = 10.0f * deltaTime;
@@ -389,11 +405,6 @@ void CameraController::update(float deltaTime) {
     if (nowStrafeLeft) movement += right;
     if (nowStrafeRight) movement -= right;
 
-    // Stand up if jumping while crouched
-    if (!uiWantsKeyboard && sitting && input.isKeyPressed(SDL_SCANCODE_SPACE)) {
-        sitting = false;
-    }
-
     // Third-person orbit camera mode
     if (thirdPerson && followTarget) {
         // Move the follow target (character position) instead of the camera