Trim over-commented Chunk 3+/4 work

A pass over the install scripts, dev-tools commands, and Hyprland Lua
files that I had stuffed with explain-everything preambles. Most of
those rationales (which files ship where, why hyprctl setenv doesn't
suffice, etc.) belong in commit messages or PR descriptions, not in
code people have to read forever. Kept the few comments that document
genuinely non-obvious behaviour: the keybind-env reason for hl.env in
envs.lua, why the runtime PAM seds stay scripted in
increase-lockout-limit, the chroot/--now distinction in chroot.sh, and
the dev-pkg-test split-install reason.

install/helpers/chroot.sh

@@ -7,14 +7,12 @@ chrootable_systemctl_enable() {
   fi
 }
 
-# Like chrootable_systemctl_enable but never passes --now, so the service is
-# only enabled for the next boot. Use for services that are either already
-# running (and re-starting would interrupt the install — iwd) or that shouldn't
-# auto-start during install (docker, power-profiles-daemon).
+# Like chrootable_systemctl_enable but never passes --now. Use for services
+# we shouldn't (re)start mid-install (iwd interrupts the network; docker and
+# power-profiles-daemon should defer to first boot).
 chrootable_systemctl_enable_only() {
   sudo systemctl enable $1
 }
 
-# Export the functions so they're available in subshells
 export -f chrootable_systemctl_enable
 export -f chrootable_systemctl_enable_only