Finish remaining ChestShop audit cleanups (dead event, garbled SQL, version-adapter scheme, deprecated double API)

Closes the ChestShop §3.7 audit items not captured by the ADT-2..46 tickets:

• Dead ShopEditedEvent — zero references; delete (audit backlog #7 "dead events").
• Garbled migration SQL — Migrations.java:143 SELECT id, code uuid FROM items-old has a stray uuid alias; fix to SELECT id, code.
• Vestigial version-adapter scheme — the reflection jar-scan loader (registerVersionedAdapters + VersionAdapter interface + isSupported()) is pointless for a single-target (Paper 1.21.11) fork. The 6 Adapter/* classes are live feature providers (iteminfo for maps/crossbows/potions/armor-trims/axolotls/bundles, sign-backside protection, physics-break, getProvides() aliasing), so collapse the scheme into direct listener registration rather than deleting the behaviour (audit backlog #7 "remove vestigial version adapters").
• Deprecated double-price/-amount API residue — PriceUtil.get/getBuyPrice/getSellPrice and the Currency*Event getDoubleAmount()/setAmount(double) overloads are production-dead (test-only); remove them.

The audit's vague "assorted NPEs" low items had no line cites; none surfaced as concrete defects in the touched files.