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

webui/public/app.js

@@ -173,6 +173,7 @@ displayForm.addEventListener('submit', async (e) => {
         enablePauseButton: fd.get('enablePauseButton') === 'on',
         enableKeyboardButton: fd.get('enableKeyboardButton') === 'on',
         enableNavButton: fd.get('enableNavButton') === 'on',
+        enableHistoryButtons: fd.get('enableHistoryButtons') === 'on',
         homeTabIndex: parseInt(fd.get('homeTabIndex'), 10),
         inactivityTimeoutMinutes: parseInt(fd.get('inactivityTimeoutMinutes'), 10),
     };
@@ -282,6 +283,7 @@ function populateAll(config) {
     displayForm.elements.enablePauseButton.checked = !!config.enablePauseButton;
     displayForm.elements.enableKeyboardButton.checked = !!config.enableKeyboardButton;
     displayForm.elements.enableNavButton.checked = !!config.enableNavButton;
+    displayForm.elements.enableHistoryButtons.checked = !!config.enableHistoryButtons;
     updateHomeTabOptions(config.tabs);
     homeTabSelect.value = String(config.homeTabIndex);
     displayForm.elements.inactivityTimeoutMinutes.value = Math.round(config.inactivityTimeout / 60);

webui/public/index.html

@@ -95,6 +95,7 @@
           <label class="checkbox"><input type="checkbox" name="enablePauseButton"> Pause button</label>
           <label class="checkbox"><input type="checkbox" name="enableKeyboardButton"> On-screen keyboard button</label>
           <label class="checkbox"><input type="checkbox" name="enableNavButton"> Navigation/help button</label>
+          <label class="checkbox"><input type="checkbox" name="enableHistoryButtons"> On-screen back/forward buttons (top middle)</label>
 
           <fieldset>
             <legend>Home page</legend>