Move non-search subcommands off /find onto /chestshop

/find had accumulated commands unrelated to finding items: shop-display toggles and an admin registry rebuild. Keep /find (and /find <item>) for item search only; move the rest onto the /chestshop (/cs) command tree, matching the existing subcommand idiom (bypass, give, metrics, notify, version).

New command surface

• /chestshop toggle visibility <true|false> (was /find toggle visibility)
• /chestshop toggle hologram <true|false> (was /find toggle hologram)
• /chestshop toggle preview <true|false> (was /find toggle preview)
• /chestshop resync <chunks> (was /find resync) — admin-only via class-level @Permission("ChestShop.admin")

Message keys renamed to match the new home:

• find.visibility-set → shop.visibility-set
• find.hologram-set → shop.hologram-set
• find.preview-set → shop.preview-set
• find.sign-target → shop.sign-target
• find.sign-no-access → shop.sign-no-access
• find.resync.* → chestshop.resync.*
• find.no-permission removed (resync is now gated by the class permission, so the manual check/message is dead)
• find.no-search unchanged (shared by the find dialog, resync, and the moved toggles)

commands/** is excluded from the coverage gate; MarketResyncServiceImpl (gated) and its test are updated for the chestshop.resync.* keys.