[Feature] Native Kits System for EternalCore

[P1otrulla]

Scope

MVP (must-have)

• kits.yml kit definitions (name, description, icon, items, optional post-claim commands)
• Kit types: recurring (cooldown), one-time, and first-join starter kits
• Per-kit permission access
• Per-kit cooldown handling
• Claim requirements (world, gamemode, minimum playtime)
• Full-inventory behavior (drop / cancel / buffer)
• Player commands: /kit, /kit , /kits, /kit info
• Admin commands: /kit give <kit, /kit resetcooldown
• Working with: /eternal reload command.
• Admin gui creator Admin Puts items in gui and they will save into kit. (maybe some /kit createkit command.
• Persistent player state in DB (claims, cooldowns, one-time usage)
• Anti-duplication safeguards for lag, relog, and concurrent claim attempts
• Full PL/EN translation support

Post-MVP extensions

• /kits GUI with availability and cooldown status
• Kit preview before claiming
• PlaceholderAPI placeholders (availability, cooldown, stats)
• Public API + events (PreKitClaimEvent, KitClaimEvent, KitCooldownExpireEvent)

Acceptance Criteria

• Servers can run kits fully without external plugins
• Claim flow is safe and duplication-resistant
• Cooldowns persist correctly across restarts
• Config and translations follow EternalCore standards