Add clan progression with level rewards

Clans and factions should earn shared experience over time. This would give teams stronger long-term goals and make recruitment more meaningful inside the Benkyy.net Minecraft community.

Suggested rewards

• Clan tags with premium color or animated variants
• Shared utility upgrades or team-based storage improvements
• Unlockable cosmetics for bases, homes, or banners
• Seasonal leaderboards with rewards for the most active groups

This system would also strengthen recruitment topics because teams could advertise clear progression goals to new members.