feat(console-menu): merge review/summary into a single diff-against-DB step

Review step now renders a box that lists only fields whose value will actually
change (old → new), with a "NEW INTERFACE" headline when no DB row exists for
the selected interface. The box is embedded into the CliMenu title so it
survives configureTerminal()->clear() on menu open — a prior stdout echo was
being wiped immediately, causing the "flashes and disappears" behaviour.

- NetworkWizard::reviewAndConfirm loads the live LanInterfaces row by
  interface name, hands it to renderChangesBoxed(), and embeds the result
  into the menu title. The intermediate "Press Enter to continue" prompt
  is gone — one screen, one decision.
- WizardHelpers::renderChangesBoxed returns the box as a string instead of
  echoing. Width 60 leaves headroom for CliMenu's margin/border/padding.
- New helpers: buildConfigDiff, labelIpv4Mode, labelIpv6Mode, labelIpv4Dns,
  labelIpv6Dns, formatDiffRow, padRight, boxTopLine, boxBottomLine, boxLine.
- IPv4 and IPv6 DNS are diffed separately, so a manual IPv6 DNS change is no
  longer masked when IPv4 is DHCP.
- Padding uses mb_strlen rather than sprintf '%-Ns' (which counts bytes), so
  UTF-8 box glyphs and em-dashes don't push columns sideways.
- Dead code removed: showConfigSummary, showConfigSummaryBoxed, and the four
  printBox* helpers — there were no other callers.

Author: boffart

src/Core/System/ConsoleMenu/Wizards/NetworkWizard.php

@@ -447,10 +447,19 @@ private function configureDNS(CliMenu $menu, string $interfaceName, array $curre
      */
     private function reviewAndConfirm(CliMenu $menu, array $config): ?bool
     {
-        $this->helpers->showConfigSummaryBoxed($config);
+        // Diff the pending config against the live DB record so the user sees
+        // only what will actually change before pressing Apply.
+        $current = LanInterfaces::findFirst([
+            'interface = :interface:',
+            'bind' => ['interface' => $config['interface']]
+        ]);
 
-        echo "\n" . $this->translation->_('cm_PressEnterToContinue') . "\n";
-        fgets(STDIN);
+        // Box is embedded in the menu title so it survives CliMenu's
+        // configureTerminal() -> clear() on open. A naive echo before
+        // $menu->open() would be wiped immediately.
+        $title = $this->translation->_('cm_ReviewConfiguration')
+            . "\n\n"
+            . $this->helpers->renderChangesBoxed($config, $current);
 
         $options = [
             'apply' => $this->translation->_('cm_ApplyConfiguration'),
@@ -460,7 +469,7 @@ private function reviewAndConfirm(CliMenu $menu, array $config): ?bool
 
         $choice = $this->helpers->showArrowChoiceMenu(
             $menu,
-            $this->translation->_('cm_ReviewConfiguration'),
+            $title,
             $options
         );