Migrate Password Protection & Lockout menu; add missing ask_time helper; bump to v2.2.0

Fifth menu migrated onto lib/menu.sh + lib/config.sh: menus/lockout.sh
covers enable/disable, changing the password, inactivity timeout, daily
lock time, and boot password. The password is SHA-256 hashed before
it's ever assigned to LOCKOUT_PASSWORD (matching main.js's comparison
logic) - verified by test that the stored value is the correct hash and
never plaintext.

Rewrote the legacy configure_password_protection's linear "ask
everything, confirm save at the end" wizard as the same immediate-save
pattern used by every other migrated menu: each action (change
password, change timeout, toggle boot password, ...) is a complete,
standalone change, consistent with Sites/Display/Timezone/Hidden PIN.
LOCKOUT_ACTIVE_START/END are deliberately left untouched - per the
Readme they're inert leftover fields the app ignores, so lib/config.sh
just carries whatever is already in config.json through unchanged.

Testing this menu surfaced a real gap before it ever shipped: lib/menu.sh
never had ask_time/validate_time at all (only validate_integer/ask_integer,
ask_url, etc were ported when the framework was first built) - "set a
daily lock time" would have failed for every single user with
"ask_time: command not found". Ported both from the legacy script.

Also promoted the ON/OFF toggle-label helper (previously private to
menus/display.sh as display_onoff) to a shared onoff() in lib/menu.sh,
since menus/lockout.sh needed the same thing and menu files should only
ever depend on lib/, never on each other.

Bumped SCRIPT_VERSION to 2.2.0 with matching changelog entries in the
script header and Readme, and updated "Modular Management" to list the
new menu and drop Password Protection & Lockout from the "not yet
migrated" list.

Verified:
- Full regression: re-ran the Sites, Display, Timezone/PIN scratch-config
  suites after every change in this round (the onoff refactor, and again
  after adding ask_time) - all still clean.
- New scratch-config test for lockout.sh: enable (password+timeout+daily
  lock+boot toggle), independently recomputed the expected SHA-256 hash
  and confirmed it matches config.json exactly, change password, change
  timeout, clear daily lock, toggle boot password, disable (confirmed
  every field clears), and that the menu builder's options correctly
  differ between the enabled and disabled states.
- End-to-end: ran the real install.sh as a genuine non-root, non-"kiosk"
  user - Lockout menu -> enable protection with a real password entered
  via the masked prompt -> set 20m timeout, 23:00 daily lock, boot
  password on -> confirmed the menu redraws with the new state -> clean
  exit (code 0). Checked the resulting config.json and file permissions
  on disk.

lib/menu.sh

@@ -38,6 +38,12 @@ log_warning() {
     echo "⚠ $*"
 }
 
+# Shared "true"/"false" -> "ON"/"OFF" label for status lines and menu
+# entries showing a boolean setting's current value.
+onoff() {
+    [[ "$1" == "true" ]] && echo "ON" || echo "OFF"
+}
+
 pause() {
     read -r -p "Press Enter to continue..."
 }
@@ -112,6 +118,30 @@ ask_integer() {
     done
 }
 
+validate_time() {
+    local time="$1"
+    [[ $time =~ ^([0-1][0-9]|2[0-3]):([0-5][0-9])$ ]]
+}
+
+ask_time() {
+    local prompt="$1"
+    local default="$2"
+    local time
+
+    while true; do
+        read -r -p "$prompt [$default]: " time
+        time="${time:-$default}"
+
+        if validate_time "$time"; then
+            echo "$time"
+            return 0
+        else
+            echo "❌ Invalid time format. Please use HH:MM (00:00 to 23:59)" >&2
+            echo >&2
+        fi
+    done
+}
+
 validate_url() {
     local url="$1"
     if [[ $url =~ ^(https?|file|data)://.*$ ]] || [[ $url =~ ^about: ]]; then