Attack indicator

• Added an animated damage indicator that smoothly moves upward.

• The duration for which the indicator is displayed can now be set in the config.

• Introduced the /atk reload command (available to operators) to reload the plugin configuration without restarting the server.

• Added a configuration option (damage-source) to filter which damage events display the indicator.

• Default config values are now:

placeholder-format: "&f{damage}&c❤"
indicator-duration: 20
animation-speed: 0.05
animation-enabled: true
damage-source: "ALL"