Add "Lock Scroll While Attacking" option

[leodesca01]

Pull request: Add "Lock Scroll While Attacking" option

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Title

Add "Lock Scroll While Attacking" option

Body

What this adds

A new opt-in option (default off) in the Mouse Settings screen:
Lock Scroll While Attacking.

When enabled, scroll events are ignored while the attack key is held down and
the player is in game (no screen or overlay open).

Why

On a Magic Mouse or a trackpad it is very easy to let a finger rest or drift
slightly while holding left click to mine. That drift is reported as a
horizontal scroll, which switches the selected hotbar item mid-mine. This makes
it possible to hold left click for a long time without accidentally changing
slots. It is useful on any mouse that can produce stray scroll input, so the
option is available on all platforms.

How it works

• The option is declared in ModOptions next to the existing ones, added to
  getModOptions() for both the macOS and non-macOS lists, and persisted in the
  mod options file as lockScrollWhileAttacking.
• The scroll is cancelled in MouseHandlerMixin (which is loaded on every
  version) with a cancellable @Inject at the head of onScroll(JDD)V. Doing it
  at onScroll means it works regardless of the downstream hotbar-scroll path
  (Inventory.scrollInHotbar on older versions vs the newer handling), so no
  extra version-conditional mixin loading is needed.
• The guard only cancels when the option is on, there is no screen/overlay open
  and the player exists, so scrolling in inventories, containers, chat and menus
  is never affected.
• The trigger is options.keyAttack.isDown(), so it follows any rebind of the
  attack key rather than assuming a hard-coded left mouse button.

Notes / points for review

• Screen/overlay checks reuse the existing pattern (ModernFabricReflectionHelper
  on 26.1+, direct field access on older versions) already used in
  MouseHandlerMixin11.
• options.keyAttack.isDown() is written with plain (Mojmap) access. I have
  built and run this on 26.2, where it works. I could not test the older
  versions locally, so the intermediary stability of keyAttack / isDown
  across 1.14 to 1.21.11 is the one thing worth confirming in CI. If you prefer,
  I can move it behind a reflection helper for the legacy target.
• No new mixin classes, no changes to MixinPlugin or the mixin json.

I have read and agree to the CONTRIBUTING terms.

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