Fix plugin security, hooks system, and admin features

- Add plugin allowlist (enabled_plugins in config.json)
- Add enable/disable toggle in admin (separate from visibility)
- Add plugin hooks system (actions + filters with auto-registration)
- Fix autoLinkPageTitles nested <a> tag vulnerability
- Move MQTT credentials to environment variables
- Preserve current page in language switcher
- Fix ctime/birthtime for file creation date
- Deduplicate getGuidePage() CommonMark setup
- Simplify formatDisplayName() logic
- Add admin activity log to dashboard
- Add own password change with current password verification
- Apply theme header_color to admin sidebar
- Add content preview button in editor

admin/templates/pages/dashboard.php

@@ -62,6 +62,26 @@
             </div>
         </div>
     </div>
+    <div class="col-md-6">
+        <div class="card shadow-sm">
+            <div class="card-header"><i class="bi bi-activity"></i> Recente activiteit</div>
+            <div class="card-body" style="max-height: 300px; overflow-y: auto;">
+                <?php if (empty($recentLogs)): ?>
+                    <p class="text-muted mb-0">Geen activiteit geregistreerd.</p>
+                <?php else: ?>
+                    <ul class="list-unstyled mb-0">
+                        <?php foreach ($recentLogs as $log): ?>
+                            <li class="mb-2 pb-2 border-bottom small">
+                                <span class="text-muted"><?= htmlspecialchars($log['time']) ?></span>
+                                <span class="badge bg-<?= $log['level'] === 'warning' ? 'warning text-dark' : ($log['level'] === 'error' ? 'danger' : 'info') ?> me-1"><?= htmlspecialchars($log['level']) ?></span>
+                                <?= htmlspecialchars($log['message']) ?>
+                            </li>
+                        <?php endforeach; ?>
+                    </ul>
+                <?php endif; ?>
+            </div>
+        </div>
+    </div>
     <div class="col-md-6">
         <div class="card shadow-sm">
             <div class="card-header"><i class="bi bi-lightning"></i> Snelle acties</div>