fix(KillAura): fall back to configured weapons when shield breaking without an axe

[Eccys]

Type of change

• Bug fix
• New feature

Description

When shield-break is enabled and a target blocks with a shield:

1. acceptableWeapon() returned stack.getItem() instanceof AxeItem unconditionally, preventing KillAura from attacking with the player's normal configured weapon when no axe is available.
2. When auto-switch is enabled and no axe is in the hotbar, InvUtils.findInHotbar(this::acceptableWeapon) returned slot = -1 (found() == false), and KillAura still called InvUtils.swap(-1, false) and marked swapped = true.

Allow axes in acceptableWeapon() when shouldShieldBreak() is true while falling back to the normal weapon filter if not holding an axe, and guard InvUtils.swap with if (weaponResult.found()).

Related issues

Closes #6611

How Has This Been Tested?

Compiled with ./gradlew compileJava and verified weapon selection and auto-switch fallback behavior.

Checklist:

• My code follows the style guidelines of this project.
• I have added comments to my code in more complex areas.
• I have tested the code in both development and production environments.

[MineGame159]

Could you resolve the merge conflict? Otherwise looks good.