Feature Request: Save Transmog Appearances from Bag 1 (Character-Based Storage)

Description

Add support to:

Save transmogrified appearances using items located in Bag 1 (backpack) as source items (not only equipped items).

Reuse the existing database saving system, but store the transformed appearance (display/entry used for transmog).

Store saved appearances per character instead of per account.

Start by tracing the existing database saving system and the code path that currently reads equipped items. Check how Bag 1 items can be selected as source items and how transformed display or entry values are represented. Done means backpack appearances are saved with the transformed value and records are isolated per character rather than per account.

Written by the indexing model from the issue text.