fix: check modifiers before useKey match in isHotkeyMatchingKeyboardEvent

The useKey early-return was bypassing modifier validation, causing
combos like ctrl+s to fire without checking if modifiers were actually
pressed. Moves the useKey check to after all modifier checks pass,
fixing dvorak/useKey mode with modifier combinations.

Fixes JohannesKlauss#1318

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: K-Mistele