Paper 26.3 support - fixes bot left/right-click doing nothing.

Fixed

• Left/right-click did nothing on Paper 26.3 - the plugin was built for 26.1.2. The accept-teleport packet now carries position and rotation in 26.3, so the server refused every bot block click; the dispatcher now sends the new format.
• PacketHelper init failed: PLAYER not found in EntityType - entity type constants moved from EntityType to EntityTypes in 26.3. The lookup now falls back to it, so bot tab-list packets work again.
• Arm swing after storage use - uses the Bukkit API (swingMainHand) since the old NMS swing call no longer exists.
• Knockback velocity sync - switched to the renamed syncVelocity flag.

Changed

• Build target - compiled against Paper 26.3.build.227-stable.

Removed

• Internal bed-sleep helper - NmsPlayerSpawner.startSleepInBed called a method that no longer exists in 26.3. It had no callers.