Bug: Seasonal event bosses (e.g. Ahune) are not balanced correctly

### Current Behaviour

When the AutoBalance module is enabled, seasonal event bosses do not scale correctly. For example, during the Midsummer Fire Festival, Ahune does not behave as expected when the module applies scaling.

On my server, everything else appears to work correctly with AutoBalance (regular dungeons, raids, and bosses), but event bosses seem to be an exception.

No crashes occur; this is a gameplay/balance issue rather than a server stability issue.

### Expected Behaviour

Seasonal event bosses, such as Ahune, should scale correctly according to the AutoBalance configuration, just like regular dungeon and raid bosses

### Steps to reproduce the problem

1. Enter the dungeon event with de LFG tool
2. Start the encounter

### Extra Notes

_No response_

### AutoBalance Debug Commands

_No response_

### AC rev. hash/commit

AzerothCore rev. 4e65712d75b4 2026-06-24 22:45:50 -400 (master branch) (Unix, RelWithDebInfo, Static)

### Operating system

Raspbian 12

### Custom changes or Modules

mod-transmog
mod-solo-lfg

Start in the AutoBalance module and reproduce the Ahune encounter through the LFG tool with scaling enabled, comparing it with a regular dungeon or raid boss. Trace how seasonal event bosses are identified and scaled; done means Ahune and similar event bosses follow the configured AutoBalance behavior without affecting existing encounters.

Written by the indexing model from the issue text.