Separate admin views from controllers — move HTML to templates/admin/

All admin pages refactored to thin controllers + pure view templates, mirroring
the public-page pattern:

Controllers (public/admin/*.php): auth, data loading, include template
Views (templates/admin/*.php): pure HTML/PHP output
Fragment partials (templates/admin/partials/): toast, system-log-panel, system-nginx-config-panel

Pages migrated: login, tags, contenus, contenus-edit, account, acces-etudiante,
thanks, add, edit, parametres, system, index

Fragment endpoints refactored: system-fragment.php, toast-fragment.php
Skipped (pure redirects): logout, logs, status, import

app/templates/admin/contenus-edit.php

@@ -0,0 +1,145 @@
+<main id="main-content">
+    <h1>Éditer : <?= htmlspecialchars($editTitle) ?></h1>
+
+    <?php if ($editType === 'page'): ?>
+    <form action="/admin/actions/page.php" method="post" class="admin-form">
+        <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION["csrf_token"]) ?>">
+        <input type="hidden" name="slug" value="<?= htmlspecialchars($pageSlug) ?>">
+
+        <label for="editor">Contenu (Markdown) :</label>
+        <input type="hidden" id="content" name="content"
+               value="<?= htmlspecialchars($initialContent) ?>">
+        <div id="editor"></div>
+
+        <div class="admin-form-footer">
+            <button type="submit" class="admin-btn">Enregistrer</button>
+            <a href="/admin/contenus.php" class="admin-btn-secondary admin-cancel-link">Annuler</a>
+        </div>
+    </form>
+
+    <?php else: ?>
+    <?php
+    $groups = is_array($value) ? $value : [];
+    ?>
+    <form action="/admin/actions/apropos.php" method="post" class="admin-form" id="apropos-form">
+        <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION["csrf_token"]) ?>">
+        <input type="hidden" name="apropos_key" value="<?= htmlspecialchars($aproposKey) ?>">
+
+        <?php foreach ($groups as $gi => $group): ?>
+        <fieldset class="apropos-group">
+            <legend><?= htmlspecialchars($aproposKey === 'contacts' ? 'Contact' : 'Crédit') ?> <?= $gi + 1 ?></legend>
+            <?php if ($aproposKey === 'contacts'): ?>
+                <label for="group_<?= $gi ?>_role">Rôle :</label>
+                <input type="text" id="group_<?= $gi ?>_role"
+                       name="groups[<?= $gi ?>][role]"
+                       value="<?= htmlspecialchars($group['role'] ?? '') ?>">
+            <?php else: ?>
+                <label for="group_<?= $gi ?>_label">Label :</label>
+                <input type="text" id="group_<?= $gi ?>_label"
+                       name="groups[<?= $gi ?>][label]"
+                       value="<?= htmlspecialchars($group['label'] ?? '') ?>">
+            <?php endif; ?>
+
+            <?php $entries = is_array($group['entries'] ?? null) ? $group['entries'] : []; ?>
+            <?php foreach ($entries as $ei => $entry): ?>
+            <div class="apropos-entry">
+                <label for="entry_<?= $gi ?>_<?= $ei ?>_text"><?= $aproposKey === 'contacts' ? 'Nom' : 'Texte' ?> :</label>
+                <input type="text" id="entry_<?= $gi ?>_<?= $ei ?>_text"
+                       name="groups[<?= $gi ?>][entries][<?= $ei ?>][text]"
+                       value="<?= htmlspecialchars($entry['text'] ?? '') ?>">
+                <?php if ($aproposKey === 'contacts'): ?>
+                    <label for="entry_<?= $gi ?>_<?= $ei ?>_email">Email :</label>
+                    <input type="email" id="entry_<?= $gi ?>_<?= $ei ?>_email"
+                           name="groups[<?= $gi ?>][entries][<?= $ei ?>][email]"
+                           value="<?= htmlspecialchars($entry['email'] ?? '') ?>">
+                <?php endif; ?>
+                <label for="entry_<?= $gi ?>_<?= $ei ?>_url">Lien (optionnel) :</label>
+                <input type="url" id="entry_<?= $gi ?>_<?= $ei ?>_url"
+                       name="groups[<?= $gi ?>][entries][<?= $ei ?>][url]"
+                       value="<?= htmlspecialchars($entry['url'] ?? '') ?>">
+            </div>
+            <?php endforeach; ?>
+
+            <button type="button" class="admin-btn admin-btn--sm add-entry-btn" data-group="<?= $gi ?>">+ Ajouter une entrée</button>
+        </fieldset>
+        <?php endforeach; ?>
+
+        <button type="button" class="admin-btn" id="add-group-btn">+ Ajouter un <?= $aproposKey === 'contacts' ? 'contact' : 'groupe de crédit' ?></button>
+
+        <div class="admin-form-footer">
+            <button type="submit" class="admin-btn">Enregistrer</button>
+            <a href="/admin/contenus.php" class="admin-btn-secondary admin-cancel-link">Annuler</a>
+        </div>
+
+        <template id="entry-template-<?= $aproposKey ?>">
+            <div class="apropos-entry">
+                <label>Entrée :</label>
+                <input type="text" name="groups[{{gi}}][entries][{{ei}}][text]">
+                <?php if ($aproposKey === 'contacts'): ?>
+                    <label>Email :</label>
+                    <input type="email" name="groups[{{gi}}][entries][{{ei}}][email]">
+                <?php endif; ?>
+                <label>Lien (optionnel) :</label>
+                <input type="url" name="groups[{{gi}}][entries][{{ei}}][url]">
+            </div>
+        </template>
+
+        <template id="group-template-<?= $aproposKey ?>">
+            <fieldset class="apropos-group">
+                <legend><?= htmlspecialchars($aproposKey === 'contacts' ? 'Contact' : 'Crédit') ?> {{gi}}</legend>
+                <?php if ($aproposKey === 'contacts'): ?>
+                    <label>Rôle :</label>
+                    <input type="text" name="groups[{{gi}}][role]">
+                <?php else: ?>
+                    <label>Label :</label>
+                    <input type="text" name="groups[{{gi}}][label]">
+                <?php endif; ?>
+                <button type="button" class="admin-btn admin-btn--sm add-entry-btn" data-group="{{gi}}">+ Ajouter une entrée</button>
+            </fieldset>
+        </template>
+    </form>
+
+    <script>
+    (function() {
+        const aproposKey = '<?= $aproposKey ?>';
+        let groupCount = <?= count($groups) ?>;
+        const entryTpl = document.getElementById('entry-template-' + aproposKey).innerHTML;
+        const groupTpl = document.getElementById('group-template-' + aproposKey).innerHTML;
+
+        // Add entry to a group
+        document.querySelectorAll('.add-entry-btn').forEach(btn => {
+            btn.addEventListener('click', function() {
+                const gi = parseInt(this.dataset.group);
+                const fieldset = this.closest('fieldset');
+                const entryCount = fieldset.querySelectorAll('.apropos-entry').length;
+                const html = entryTpl.replaceAll('{{gi}}', gi).replaceAll('{{ei}}', entryCount);
+                this.insertAdjacentHTML('beforebegin', html);
+            });
+        });
+
+        // Add new group
+        document.getElementById('add-group-btn').addEventListener('click', function() {
+            groupCount++;
+            const html = groupTpl.replaceAll('{{gi}}', groupCount);
+            this.insertAdjacentHTML('beforebegin', html);
+
+            // Re-bind add-entry buttons for the new group
+            const newGroup = this.previousElementSibling;
+            if (newGroup && newGroup.classList.contains('apropos-group')) {
+                const btn = newGroup.querySelector('.add-entry-btn');
+                if (btn) {
+                    btn.dataset.group = groupCount;
+                    btn.addEventListener('click', function() {
+                        const gi = parseInt(this.dataset.group);
+                        const fieldset = this.closest('fieldset');
+                        const entryCount = fieldset.querySelectorAll('.apropos-entry').length;
+                        const html = entryTpl.replaceAll('{{gi}}', gi).replaceAll('{{ei}}', entryCount);
+                        this.insertAdjacentHTML('beforebegin', html);
+                    });
+                }
+            }
+        });
+    })();
+    </script>
+    <?php endif; ?>
+</main>