Afficher les prochains événements du calendrier public sur la page d'accueil

- Ajoute web/inc/calendar.php : récupère le flux iCal via ?p=webcal,
  cache le résultat 1h dans /tmp, parse les VEVENT à venir
- Intègre le bloc "Prochains événements" dans index.php avant les services

Closes #1

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/inc/calendar.php

@@ -0,0 +1,47 @@
+<?php
+
+function calendar_next_events(int $n = 5): array {
+    $url   = 'https://alpinux.org/public-calendars/n5BWPYsxw7FCYozM?p=webcal';
+    $cache = sys_get_temp_dir() . '/alpinux_calendar.ics';
+    $ttl   = 3600;
+
+    if (!file_exists($cache) || (time() - filemtime($cache)) >= $ttl) {
+        $data = @file_get_contents($url);
+        if ($data !== false) file_put_contents($cache, $data);
+    }
+
+    if (!file_exists($cache)) return [];
+
+    return _ical_upcoming(file_get_contents($cache), $n);
+}
+
+function _ical_upcoming(string $ical, int $n): array {
+    $events = [];
+    $now    = time();
+
+    preg_match_all('/BEGIN:VEVENT(.+?)END:VEVENT/s', $ical, $blocks);
+
+    foreach ($blocks[1] as $b) {
+        $e = [];
+
+        if (preg_match('/^SUMMARY[^:]*:(.+)$/m', $b, $m))
+            $e['title'] = trim($m[1]);
+
+        if (preg_match('/^LOCATION[^:]*:(.+)$/m', $b, $m))
+            $e['location'] = trim($m[1]);
+
+        if (preg_match('/^DTSTART[^:]*:(\d+)/m', $b, $m)) {
+            $r = $m[1];
+            $e['start'] = strlen($r) === 8
+                ? mktime(0, 0, 0, substr($r, 4, 2), substr($r, 6, 2), substr($r, 0, 4))
+                : strtotime($r);
+        }
+
+        if (isset($e['start'], $e['title']) && $e['start'] >= $now)
+            $events[] = $e;
+    }
+
+    usort($events, fn($a, $b) => $a['start'] - $b['start']);
+
+    return array_slice($events, 0, $n);
+}

web/index.php

@@ -2,6 +2,7 @@
 require_once __DIR__ . '/inc/config.php';
 require_once __DIR__ . '/inc/auth.php';
 require_once __DIR__ . '/inc/services.php';
+require_once __DIR__ . '/inc/calendar.php';
 
 session_start_safe();
 
@@ -64,6 +65,20 @@ require __DIR__ . '/views/layout.php';
 
 <?php endif; ?>
 
+<?php $calendar_events = calendar_next_events(5); if ($calendar_events): ?>
+<section class="calendar-section">
+  <h2>Prochains événements</h2>
+  <div class="about-grid">
+    <?php foreach ($calendar_events as $ev): ?>
+    <div class="about-card">
+      <div class="about-title"><?= htmlspecialchars($ev['title']) ?></div>
+      <p><?= date('d/m/Y', $ev['start']) ?><?= !empty($ev['location']) ? ' — ' . htmlspecialchars($ev['location']) : '' ?></p>
+    </div>
+    <?php endforeach; ?>
+  </div>
+</section>
+<?php endif; ?>
+
 <section class="services-section">
   <h2>Nos services</h2>
   <div class="grid">