feat(site): per-gym SEO texts, event gym selector, hero/navbar polish

- Generated SEO titles/descriptions per gym; gym seo fields override each on its own
- Keywords, author, og:site_name, favicon and JSON-LD logo follow the gym
- CrossFit page 404s before output for gyms without a box
- Events: «Mostrar em» gym selector; event page uses its gym's brand
- Hero event button text colour from the event colour (--ev-on)
- Navbar bottom line stops at the other-gym head (--switch-w)
- Diagonal hero blur mask; remove the trial link

site/evento.php

@@ -105,8 +105,12 @@ $seo_desc  = $event['summary'] !== ''
     : trim(mb_substr(strip_tags((string) ($event['subtitle'] ?: $event['description'])), 0, 200));
 
 $current_uri_2 = 'evento';
+// An event tied to one gym (Eventos → «Mostrar em») renders in that gym's brand.
+$ev_gym = !empty($event['gym_id']) ? db_gyms_get($pdo, (int) $event['gym_id']) : null;
+if ($ev_gym && empty($_GET['gym'])) $_GET['gym'] = $ev_gym['slug'];
+$ev_gym = $ev_gym ?? site_gym($pdo) ?? gym_fallback();
 $GLOBALS['_page_meta_override'] = [
-    ($event['title'] !== '' ? $event['title'] : 'Evento') . ' | FitMe 3070',
+    ($event['title'] !== '' ? $event['title'] : 'Evento') . ' | ' . $ev_gym['name'],
     $seo_desc,
 ];
 $GLOBALS['_canonical_override'] = $event_url;
@@ -114,7 +118,7 @@ $GLOBALS['_og_type_override']   = 'article';
 if ($hero_url !== '') $GLOBALS['_og_image_override'] = $hero_url;
 
 // Event structured data (schema.org/Event) for rich link previews / search.
-$info = site_info($pdo);
+$info = site_info($pdo, (int) $ev_gym['id']);
 $ld_event = [
     '@context'    => 'https://schema.org',
     '@type'       => 'Event',
@@ -130,11 +134,11 @@ if (!empty($event['event_ends_at']))   $ld_event['endDate']   = str_replace(' ',
 $ld_event['location'] = $event['location'] !== ''
     ? ['@type' => 'Place', 'name' => $event['location']]
     : ['@type' => 'Place',
-       'name'    => ($info['name'] ?? '') !== '' ? $info['name'] : 'FitMe 3070',
+       'name'    => ($info['name'] ?? '') !== '' ? $info['name'] : $ev_gym['name'],
        'address' => $info['adress'] ?? ''];
 $ld_event['organizer'] = [
     '@type' => 'Organization',
-    'name'  => ($info['name'] ?? '') !== '' ? $info['name'] : 'FitMe 3070',
+    'name'  => ($info['name'] ?? '') !== '' ? $info['name'] : $ev_gym['name'],
     'url'   => base_url(),
 ];
 $GLOBALS['_jsonld_extra'] = $ld_event;