fix: slows and speed buffs change enemy movement speed

Speed buffs (BuffParameters "speed", for example the slow from the Great
Katana of Freezing and the Shurikens of Ice) and speed behaviours go
through ControllablePhysicsComponent's speed multiplier, which only
players' clients used. Enemies move with MovementAIComponent, which
ignored it, so slows had no effect on them.

- MovementAIComponent scales its waypoint speed by the entity's speed
  multiplier when one is set.
- RemoveSpeedboost set the multiplier of any entity without a
  LevelProgressionComponent (every enemy and pet) to 0 once its last
  boost ended, which was harmless while nothing read it for them. It now
  goes back to the normal base of 500 (multiplier 1).

Needs an in-game check with the freezing katana charge-up against an
enemy.

Fixes #1179

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dGame/dComponents/ControllablePhysicsComponent.cpp

@@ -289,7 +289,7 @@ void ControllablePhysicsComponent::RemoveSpeedboost(float value) {
 	}
 
 	// Recalculate speedboost since we removed one
-	m_SpeedBoost = 0.0f;
+	m_SpeedBoost = 500.0f; // Entities without level progression (enemies, pets) go back to the normal multiplier of 1
 	if (m_ActiveSpeedBoosts.empty()) { // no active speed boosts left, so return to base speed
 		auto* levelProgressionComponent = m_Parent->GetComponent<LevelProgressionComponent>();
 		if (levelProgressionComponent) m_SpeedBoost = levelProgressionComponent->GetSpeedBase();