Few minor critical fixes for WorldReset 1.5fix

🐛 Fixed Bugs & Technical Improvements

• 🌍 Paper/Purpur 1.21+ Multi-World Support: Redesigned world unloading, deleting, and backing up to fully support modern Paper directory structures (.\world\dimensions\) in addition to legacy Spigot structures.
• 🌬️ Watchdog & Windows File Lock Delay: Added a 20-tick (1-second) cooldown before deleting folders to let Spigot's async threads complete chunk saving and release OS file locks cleanly (fully compatible with Aikar's Flags).
• 🛡️ Defensive Limbo Loading: Wrapped limbo world loading in a fallback block that automatically generates a safe flat world in case of server migration conflicts, preventing server start crashes.
• 🔑 Granular Permissions Fix: Removed global worldreset.admin block in commands, allowing players to use their granular permissions (e.g. worldreset.limbo), and added missing checks for reload, silent, and death.
• 🚪 Adventure Mode Offline Join Fix: Solved the bug where offline players joining after game start were stuck in Limbo's Adventure mode instead of starting in Survival.
• ⏱️ Individual Timer Freeze Fix: Resolved stuck individual timers (0:00) by ensuring player start times are correctly initialized when they first tick.
• 🏹 Spawn Shifter Search Crash Protection: Prevented world generation tasks from crashing in case a structure search throws registry exceptions.
• ⚙️ Difficulty Persistence: World difficulty is now permanently saved to config.yml on world resets so it is correctly loaded after server reboots.
• 📦 Fixed Seed NPE Protection: Prevented server startup crashes when use-fixed seed is enabled but no value is specified in configuration.

Thanks for reporting bugs on Discord—I make a lot of them.