Page back/forward: Alt+Left/Right, mouse side buttons, optional on-screen buttons

Alt+Left/Right now go back/forward within the page (the standard browser
keys) instead of switching sites; sites switch with Ctrl+Tab, Ctrl+[ ] and
the standard Ctrl+PageUp/PageDown. New enableHistoryButtons option (off by
default) shows half-transparent back/forward buttons at the top middle.
Settable from the terminal menu and the Web UI.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013wi3ZQveYdjfcrEsyazq32

menus/display.sh

@@ -20,6 +20,7 @@ display_status() {
     echo "Pause button:       $(onoff "$ENABLE_PAUSE_BUTTON")"
     echo "Keyboard button:    $(onoff "$ENABLE_KEYBOARD_BUTTON")"
     echo "Navigation button:  $(onoff "$ENABLE_NAV_BUTTON")"
+    echo "Back/forward btns:  $(onoff "$ENABLE_HISTORY_BUTTONS")"
 }
 
 display_menu_builder() {
@@ -29,6 +30,7 @@ display_menu_builder() {
         "Toggle pause button (currently: $(onoff "$ENABLE_PAUSE_BUTTON"))"
         "Toggle on-screen keyboard button (currently: $(onoff "$ENABLE_KEYBOARD_BUTTON"))"
         "Toggle navigation/help button (currently: $(onoff "$ENABLE_NAV_BUTTON"))"
+        "Toggle on-screen back/forward buttons (currently: $(onoff "$ENABLE_HISTORY_BUTTONS"))"
     )
     MENU_HANDLERS=(
         action_set_touch_mode
@@ -36,6 +38,7 @@ display_menu_builder() {
         action_toggle_pause_button
         action_toggle_keyboard_button
         action_toggle_nav_button
+        action_toggle_history_buttons
     )
 }
 
@@ -131,3 +134,18 @@ action_toggle_nav_button() {
     fi
     save_config
 }
+
+# Page back/forward: Alt+Left / Alt+Right and the mouse's side buttons
+# always work; this adds clickable buttons (top middle, half transparent,
+# shown on mouse movement or a tap) for screens with no keyboard or mouse
+# buttons. Off by default.
+action_toggle_history_buttons() {
+    if [[ "$ENABLE_HISTORY_BUTTONS" == "true" ]]; then
+        ENABLE_HISTORY_BUTTONS="false"
+        log_warning "On-screen back/forward buttons disabled"
+    else
+        ENABLE_HISTORY_BUTTONS="true"
+        log_success "On-screen back/forward buttons enabled"
+    fi
+    save_config
+}