Add proper waypoint support to entity movement:
- Parse intermediate waypoints from MonsterMove packets in both WotLK
and Vanilla paths. Uncompressed paths store absolute float3 waypoints;
compressed paths decode TrinityCore's packed uint32 deltas (11-bit
signed x/y, 10-bit signed z, ×0.25 scale, waypoint = midpoint − delta)
with correct 2's-complement sign extension.
- Entity::startMoveAlongPath() interpolates along cumulative-distance-
proportional segments instead of a single straight line.
- MovementHandler builds the full path (start → waypoints → destination)
in canonical coords and dispatches to startMoveAlongPath() when
waypoints are present.
- Snap entity x/y/z to moveEnd in the dead-reckoning overrun phase
before starting a new movement, preventing visible teleports when the
renderer was showing the entity at its destination.
- Clamp creature and player entity Z to the terrain surface via
TerrainManager::getHeightAt() during active movement. Idle entities
keep their server-authoritative Z to avoid breaking flight masters,
elevator riders, etc.
Signed-off-by: Pavel Okhlopkov <pavel.okhlopkov@flant.com>
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