source single startup file instead of inlining Hyprland config or lua file

[notcandy001]

Overview

Replaces the inline exec-once (hyprland.conf) / hl.on (hyprland.lua) block that
the installer appended into the user's Hyprland config with a single-line
injection instead.

• Startup commands now live in dots-extra/templates/startup.conf.tpl /
  startup.lua.tpl. The installer renders these (substituting the detected
  keyboard layout) to ~/.config/hypr/brain-shell-startup.conf / .lua,
  and injects just one line into the user's own config:
  • source = $HOME/.config/hypr/brain-shell-startup.conf
  • dofile(os.getenv("HOME") .. "/.config/hypr/brain-shell-startup.lua")
• The injected line is wrapped in >>>/<<< markers so re-running the
  installer finds and replaces it instead of duplicating it on reinstall.
• Also detects and strips the old fully-inlined block from pre-existing
  installs, so upgrading from an older Brain Shell leaves a clean config.
• Added keyboard layout auto-detection (localectl, falling back to the
  live hyprctl device list when run inside an active Hyprland session),
  baked into the generated startup file's input block.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (causes existing functionality to not work as expected)

Testing Checklist

• I have tested these changes locally and on a fresh VM install.
• I have tested the QML UI on my primary resolution.
• (If applicable) I have tested UI changes on secondary monitors or different resolutions.
• (If applicable) I have verified my bash scripts run cleanly without syntax errors.

Related Issues

(link the issue/discussion this addresses, if any)

[Brainitech]

Everything Looks good, but I suggest you retain the comments removed in install-arch.sh

[notcandy001]

done 👍🏽