## Summary

This commit implements a new SmartAI target type SMART_TARGET_SUMMONED_ENTRY that allows SmartAI scripts to find summoned creatures (pets, vehicles, or other controlled units) by their entry ID.

## Problem

Previously, SmartAI scripts had no way to target specific summoned creatures by their entry ID. There was no target type that could:

- Find pets or vehicles summoned by a specific unit
- Match summoned creatures by their creature entry
- Support both SAI source object's summons and invoker's summons

## Solution

Added SMART_TARGET_SUMMONED_ENTRY target type with the following parameters:

- target_param1 : Summoned creature entry to target
- target_param2 : Summoner source
  - 0 : SAI source object's summons
  - 1 : Current SmartAI invoker's summons

The implementation:

1. Validates the summoner parameter
2. Retrieves the summoner unit based on parameter
3. Iterates through the summoner's m_Controlled list
4. Filters by entry ID and world presence

## Impact

- Adds new functionality without breaking existing features
- Supports all controlled unit types (pets, vehicles, guardians)
- Includes proper validation and debug logging
- Fixed null pointer safety by checking ToUnit() result before assignment
to prevent potential crashes when scriptTrigger is not a Unit type.