Add massage as a third vertical, driven by a config registry

Introduces /massage alongside barber and beauty: landing page, booking
flow, admin support, home tile and SEO entries, in all three languages.

Architecture
- application/config/verticals.php + vertical_helper.php: one registry
  entry per vertical (branding, assets, views, behaviour flags). A fourth
  vertical is a config entry plus content files.
- Strangler: barber and beauty keep pointing at their existing view files,
  so their rendered HTML is unchanged. Only massage uses the new generic
  pages/vertical-*.php and includes/vertical-*.php views, which collapse
  the four duplicated per-language nav/footer branches into one.
- Pages::vertical() + one route; booking(), booking_finished(),
  _booking_error() and manage_booking() are now registry-driven.

Worker/vertical coupling
- getActiveWorkers() derives the vertical from services.service_category_id
  instead of the workers.is_barber / is_beauty flags, which were a
  hand-maintained cache of exactly that fact. Verified against production
  data: the derived set reproduced the stored flags for every worker, in
  both verticals. No schema change was needed for massage.
- The legacy flags are now written through from the category so a rollback
  cannot strand a new worker, and the admin worker UI shows the derived
  verticals read-only instead of two dropdowns that controlled nothing.

Bug fixes found along the way (all pre-existing)
- booking_process() had no server-side category guard; cross-vertical
  mixing was prevented only by client-side JS.
- add-service-form / add-worker-form emitted `selected` on every category
  option, so the newest category silently became the default.
- update-service-form offered only barber/beauty, so editing a service of
  any other type silently rewrote it.
- getWorkerScheduleByDay ignored schedule overrides while getAvailableTimes
  honoured them, so slots could be shown and then rejected. Added an
  override-aware getWorkerScheduleForDate() and used it in both guards.
- Booking lists dereferenced a null service if one had been hard-deleted.
- main.css: .tiles was tuned for exactly two tiles, including an
  absolutely-positioned .style1 at the 1280px breakpoint.

Massage-specific behaviour, opt-in per vertical
- strip_category_prefix: grouped service lists show "50 min" under the
  treatment heading rather than repeating the full name. The full name is
  carried in data-service-name so the totals panel stays unambiguous, and
  services.service_name is untouched for emails and admin.
- single_service_booking: one treatment per booking, enforced in the UI and
  in booking_process(). Re-clicking the selection releases it.
- Displayed treatment time (50/80/110 min) is in the service name; the
  booked slot (60/90/120 min) is service_time and covers changing and
  payment. service_time is never shown to the guest.

DB migrations for dev/prod are in documents/ - additive only, no ALTER.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

application/views/includes/vertical-header.php

@@ -0,0 +1,59 @@
+<?php
+/**
+ * Generic site header for any vertical.
+ *
+ * Expects $vertical and $selectedLang.
+ *
+ * The per-vertical headers this replaces carried FOUR near-identical copies of
+ * the same <ul> - one per language plus an unlabelled else-fallback that was
+ * reached whenever $selectedLang was not en/hu/no (and which referenced
+ * $currentPageUrlArray before it was defined). Here there is one nav and one
+ * label table, so the fallback cannot drift from the real branches.
+ */
+
+$labels = array(
+    'en' => array(
+        'home' => 'Home', 'about' => 'About US', 'treatments' => 'Treatments',
+        'prices' => 'Prices', 'hours' => 'Opening Hours', 'contact' => 'Contact',
+        'book' => 'BOOK TIME',
+    ),
+    'no' => array(
+        'home' => 'Forside', 'about' => 'Om oss', 'treatments' => 'Behandlinger',
+        'prices' => 'Priser', 'hours' => 'Åpningstider', 'contact' => 'Kontakt',
+        'book' => 'BESTILL TIME',
+    ),
+    'hu' => array(
+        'home' => 'Kezdőlap', 'about' => 'Rólunk', 'treatments' => 'Szolgáltatások',
+        'prices' => 'Árlista', 'hours' => 'Nyitvatartás', 'contact' => 'Kapcsolat',
+        'book' => 'IDŐPONTFOGLALÁS',
+    ),
+);
+
+$lang = vertical_lang(isset($selectedLang) ? $selectedLang : 'en');
+$t    = $labels[$lang];
+
+// Language switcher: rebuild the current URL with a different language segment.
+// Segment 1 is the language, 2 and 3 are the page path.
+$currentPageUrlArray = explode('/', $_SERVER['REQUEST_URI']);
+$currentPageUrlArray += array(1 => '', 2 => '', 3 => '');
+?>
+<!-- Header -->
+<header id="header">
+    <a href="<?php echo SITEURL;?>"><img src="<?php echo SITEURL;?>assets/img/<?php echo $vertical['logo'];?>" class="logo-kep"></a> <h1><?php echo htmlspecialchars($vertical['heading'], ENT_QUOTES, 'UTF-8');?></h1>
+    <nav id="nav">
+        <ul>
+            <li><a href="<?php echo SITEURL;?>"><?php echo $t['home'];?></a></li>
+            <li><a href="#aboutus"><?php echo $t['about'];?></a></li>
+            <li><a href="#treatments"><?php echo $t['treatments'];?></a></li>
+            <li><a href="#one"><?php echo $t['prices'];?></a></li>
+            <li><a href="#two"><?php echo $t['hours'];?></a></li>
+            <li><a href="#footer"><?php echo $t['contact'];?></a></li>
+            <li class="booktime"><a href="<?php echo SITEURL.$lang.'/booking/'.$vertical['slug'];?>"><?php echo $t['book'];?></a></li>
+            <li class="socialmedia-menu"><a href="<?php echo $vertical['facebook'];?>" class="icon brands fa-facebook-f"><span class="label">Facebook</span></a></li>
+            <li class="socialmedia-menu"><a href="<?php echo $vertical['instagram'];?>" class="icon brands fa-instagram"><span class="label">Instagram</span></a></li>
+            <?php foreach(array('no', 'en', 'hu') as $switchLang): ?>
+            <li class="language"><a href="<?php echo SITEURL.$switchLang.'/'.$currentPageUrlArray[2].'/'.$currentPageUrlArray[3];?>"><?php echo strtoupper($switchLang);?></a></li>
+            <?php endforeach; ?>
+        </ul>
+    </nav>
+</header>