Add omarchyiso for building a custom ISO

[tahayvr]

This PR adds a script called omarchyiso that enables Omarchy users to create customized ISO images with their personal configurations and packages.

This feature:

• let's us duplicate our personalized systems on new machines. Imagine omarchy installs in 2 mins, but now it has your exact configs and apps. ready to go.
• Enables other Orgs to create a customized omarchy ISO for their users.

These types of things need to be tested on different devices. So sharing this as a draft for feedback

The script allows users to:

1. Select installed AUR packages
   • script automatically detects any installed package that is not from the official Arch repo with pacman -Qmq

2. Input official Arch packages
   • For now, user has to manually enter the names of any package they want from the official Arch repo (working on automating this if possible)

3. Select .config folders
   • script lists the folders in ~/.config and allows user to select which ones to include in the ISO. These will end up in the user's .local/share/omarchy/config

4. Review configuration summary

6. Build the ISO

How it works

The tool:

• Clones omarchy-iso repository into a omarchyiso-build folder
• Copies selected dotfiles to configs/airootfs/root/custom-config/
• lists selected AUR packages in builder/custom-aur.packages
• lists selected official packages in builder/custom-arch.packages

The next two steps should ideally be implemented upstream. If this idea is approved, The omarchy-iso repo can suppport the script by already including these lines.

• Modifies .automated_script.sh to overlay custom configs during installation
• Modifies build-iso.sh to include custom/AUR packages in offline mirror

Finally:

• Runs omarchy-iso-make to build the ISO.

Styling and UI need work.