fix(installer): allow root execution in archiso by shimming sudo

When running as root (archiso chroot context), all three TUI installers
previously died immediately. Replace the hard die with a sudo passthrough
shim ($TMP_D/bin/sudo → exec "$@") prepended to PATH, so every module's
`sudo pacman`, `sudo systemctl` etc. just executes directly as root.
The shim lives in TMP_D and is cleaned up by the existing EXIT trap.

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

setup/install-modules.sh

@@ -149,7 +149,13 @@ count_steps() {
     [[ "$sel" == *"kate"*            ]] && TOTAL=$(( TOTAL + 1 ))
 }
 
-[[ $EUID -eq 0 ]] && die "Run as your normal user (not root)."
+if [[ $EUID -eq 0 ]]; then
+    # Root context (e.g. archiso chroot): shim sudo as a passthrough
+    mkdir -p "$TMP_D/bin"
+    printf '#!/bin/bash\nexec "$@"\n' > "$TMP_D/bin/sudo"
+    chmod +x "$TMP_D/bin/sudo"
+    export PATH="$TMP_D/bin:$PATH"
+fi
 command -v pacman &>/dev/null || die "pacman not found — Arch Linux required."
 
 require_dialog

setup/simple-install.sh

@@ -395,7 +395,13 @@ get_mac_suffix() {
 }
 
 # ── Preflight ─────────────────────────────────────────────────────────────────
-[[ $EUID -eq 0 ]] && die "Run as your normal user (not root)."
+if [[ $EUID -eq 0 ]]; then
+    # Root context (e.g. archiso chroot): shim sudo as a passthrough
+    mkdir -p "$TMP_D/bin"
+    printf '#!/bin/bash\nexec "$@"\n' > "$TMP_D/bin/sudo"
+    chmod +x "$TMP_D/bin/sudo"
+    export PATH="$TMP_D/bin:$PATH"
+fi
 command -v pacman &>/dev/null || die "pacman not found — Arch Linux required."
 
 if $ANSWERFILE_MODE; then

setup/tui-install.sh

@@ -220,7 +220,13 @@ get_mac_suffix() {
 }
 
 # ── Preflight ─────────────────────────────────────────────────────────────────
-[[ $EUID -eq 0 ]] && die "Run as your normal user (not root)."
+if [[ $EUID -eq 0 ]]; then
+    # Root context (e.g. archiso chroot): shim sudo as a passthrough
+    mkdir -p "$TMP_D/bin"
+    printf '#!/bin/bash\nexec "$@"\n' > "$TMP_D/bin/sudo"
+    chmod +x "$TMP_D/bin/sudo"
+    export PATH="$TMP_D/bin:$PATH"
+fi
 command -v pacman &>/dev/null || die "pacman not found — Arch Linux required."
 
 require_dialog