Restore Tibia 8.60 Knight spell learning

[adrunkhuman]

Summary

• Restore the sourced Tibia 8.60 Knight spell registry, trainer inventories, prices, premium gates, vocation eligibility, and learned-state requirements.
• Register Wound Cleansing, remove post-8.60 Knight offers, and repair shared trainer keyword handling for specific spell names and premium checks.
• Add executable contract and connectionless regressions for normal purchases, persistence, duplicate handling, and eligibility failures.

Verification

• pwsh -File scripts/test-knight-spell-contract.ps1 - passed
• Connectionless spellTrainer, spellFailures, and spellReset -> spellLearning -> spellPersistence modes - passed against a clean database with clean server stops
• Manual client purchases and casts through Gregor, Puffels, Ursula, Eremo, Zoltan, and Eliza - passed

Notes

Spell damage, healing formulas, and effects remain under #1. The shared 8.60 public name Antidote remains under #94.

Closes #89