[chestshop] Unified /chestshop command tree + admin self-bypass toggle

Reworked ChestShop's scattered, cryptically-named commands into one tree, matching the Treasury/Business style, and added an admin self-bypass toggle.

New unified root /chestshop (alias /cs), via the framework Commander + HelpGenerator:

• /chestshop / /chestshop help [page] — paginated, permission-filtered help
• /chestshop bypass — NEW: toggle your own admin bypass
• /chestshop access (was /csaccess), /chestshop notify (was /cstoggle)
• /chestshop give <…> (was /csGive), /chestshop metrics (was /csMetrics)
• /chestshop version / /chestshop reload (was /csVersion …)
• /iteminfo and /shopinfo stay standalone (high-frequency lookups)

Admin bypass (AdminBypass): staff normally hold ChestShop.admin/mod/… which let them open/break any shop and trade without being a real customer. /chestshop bypass lets a staff member opt out so they can play — charged for trades, no access to others' shops — and flip it back on. The whole mechanic rides on one gate: Permission.has(...) returns false for the elevated "staff" nodes while a player is opted out, so every admin-gated path demotes them with no per-call-site changes. The toggle command stays reachable because the framework's @Permission uses Bukkit's raw hasPermission, not Permission.has. State is in-memory (resets on restart → bypass re-granted by default, the safe failure mode), mirroring the existing access toggle.

Verified: builds + tests green; ChestShop enables; the multi-handler command root registers with no route conflicts.