Item pages that link vendors, sets, Stigmas, skill books and instances in both directions

Many of these links already exist: which vendors sell an item and for what, set members and bonuses, which item teaches which Stigma or skill, and instance exits. We plan to finish the rest and make sure every link works both ways with the right details attached.

- Vendor stock shows the quantity and the currency or item it costs. - Set pages show how many pieces each bonus needs. - Skills link back to the books and Stigma stones that teach them, at the exact class and level. - Crafting combo products and NPC worn equipment get their own links. - Item pages can show current Broker listings with how fresh they are, once that source is in place.

Vendor price multipliers are only applied once we know exactly how the game uses them.