Add event catalogue page with retention and purge support

[tudddorrr]

Event catalogue page

• New paginated table view listing all events with name, total count, unique players, and prop keys
• Inline retention management: admins can set, edit, and clear retention days per event
• Purge button for admins to delete all instances of a specific event with confirmation dialog
• Route added at /events/catalogue with lazy loading

Permissions

• Added PURGE_EVENTS and CHANGE_EVENT_RETENTION to PermissionBasedAction enum
• Both actions restricted to ADMIN users
• Purge and retention edit UI elements hidden for non-admin users