Classic 1.12 trainer list entries lack the profDialog and profButton
uint32 fields (8 bytes) that TBC/WotLK added before reqLevel. Instead,
reqLevel immediately follows spellCost, and a trailing unk uint32 appears
at the end of each entry. Parsing the WotLK format for Classic caused
misalignment from the third field onward, corrupting state, cost, level,
skill, and chain data for all trainer spells.
- TrainerListParser::parse() gains a isClassic bool parameter (default false)
- Classic path: cost(4) → reqLevel(1) → reqSkill... → chainNode3 → unk(4)
- WotLK/TBC path: cost(4) → profDialog(4) → profButton(4) → reqLevel(1) → reqSkill...
- handleTrainerList() passes isClassicLikeExpansion() as the flag