Add keymap hook for keyboard layout support

[jardahrazdera]

Summary

This PR adds proper keyboard layout support for non-US layouts during LUKS unlock and live session operations by adding the keymap hook to mkinitcpio configuration.

Changes

• Added builder/patches/keymap-hook.patch - patches archiso mkinitcpio configuration
• Positions keymap hook after keyboard hook - follows Arch Wiki best practices
• Uses patch-based approach - no direct submodule modifications as requested

Technical Details

The patch modifies airootfs/etc/mkinitcpio.conf.d/archiso.conf:

-HOOKS=(base udev microcode modconf kms memdisk archiso archiso_loop_mnt archiso_pxe_common archiso_pxe_nbd archiso_pxe_http archiso_pxe_nfs block filesystems keyboard)
+HOOKS=(base udev microcode modconf kms keyboard keymap memdisk archiso archiso_loop_mnt archiso_pxe_common archiso_pxe_nbd archiso_pxe_http archiso_pxe_nfs block filesystems)

Problem Solved

Addresses part of #31 - specifically the keyboard layout component of LUKS unlock failures.

Users with non-US keyboard layouts (Polish, German, etc.) experience issues during LUKS password entry because:

1. Password is set with local layout during installation
2. Boot-time unlock defaults to US layout without keymap hook
3. Users cannot enter correct password characters

Note: Issue #31 may have additional causes beyond keyboard layout (hardware-specific issues, driver problems, etc.). This PR specifically resolves the keyboard layout mismatch component.

Testing

• Patch applies cleanly during build process
• No interference with existing archiso functionality
• Hook order follows Arch Linux documentation
• Resolves keyboard layout mismatch issues

References

• Partially fixes Some users report LUKS unlock failures during boot #31
• Related discussion: Consider optional encryption basecamp/omarchy#1281
• Arch Wiki: dm-crypt/Encrypting an entire system
• Previous submodule-based approach correctly identified the need but used wrong implementation method