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/thanks.php

@@ -0,0 +1,115 @@
+<main id="main-content">
+    <?php if ($studentMode): ?>
+    <!-- ═══════════════════ STUDENT MODE: Thank you page ═══════════════════ -->
+    <div class="thanks-student-page">
+        <?php if ($error): ?>
+            <div class="thanks-error">
+                <h1>⚠ Oups…</h1>
+                <p><?= htmlspecialchars($error) ?></p>
+                <a href="/admin/add.php?mode=student" class="btn-new-form">← Retour au formulaire</a>
+            </div>
+
+        <?php elseif ($thesis): ?>
+            <div class="thanks-success">
+                <h1>Merci 🎉</h1>
+                <p class="thanks-message">
+                    Ton TFE <strong><?= htmlspecialchars($thesis['title']) ?></strong> a bien été soumis.
+                </p>
+                <a href="/admin/add.php?mode=student" class="btn-new-form">+ Ajouter un nouveau TFE</a>
+            </div>
+        <?php else: ?>
+            <div class="thanks-error">
+                <h1>Erreur</h1>
+                <p>Aucune donnée à afficher.</p>
+                <a href="/admin/add.php?mode=student" class="btn-new-form">← Retour au formulaire</a>
+            </div>
+        <?php endif; ?>
+    </div>
+
+    <?php else: ?>
+    <!-- ═══════════════════ ADMIN MODE: Recap page ═══════════════════ -->
+    <h1>Récapitulatif TFE</h1>
+
+    <?php if ($error): ?>
+        <p class="toast" role="alert" data-type="error">⚠ <?= htmlspecialchars($error) ?></p>
+        <p><a href="/admin/add.php" class="admin-btn-secondary">Retour au formulaire</a></p>
+
+    <?php elseif ($thesis): ?>
+        <section>
+            <h2>Informations de base</h2>
+            <dl>
+                <dt>Identifiant</dt><dd><?= htmlspecialchars($thesis['identifier']) ?></dd>
+                <dt>Titre</dt><dd><?= htmlspecialchars($thesis['title']) ?></dd>
+                <?php if ($thesis['subtitle']): ?>
+                <dt>Sous-titre</dt><dd><?= htmlspecialchars($thesis['subtitle']) ?></dd>
+                <?php endif; ?>
+                <dt>Auteur·ice(s)</dt><dd><?= htmlspecialchars($thesis['authors']) ?></dd>
+                <dt>Année</dt><dd><?= htmlspecialchars($thesis['year']) ?></dd>
+            </dl>
+        </section>
+
+        <section>
+            <h2>Détails académiques</h2>
+            <dl>
+                <dt>Orientation</dt><dd><?= htmlspecialchars($thesis['orientation'] ?? '–') ?></dd>
+                <dt>Atelier pratique</dt><dd><?= htmlspecialchars($thesis['ap_program'] ?? '–') ?></dd>
+                <dt>Finalité</dt><dd><?= htmlspecialchars($thesis['finality_type'] ?? '–') ?></dd>
+                <?php if ($thesis['supervisors']): ?>
+                <dt>Promoteur·ice(s)</dt><dd><?= htmlspecialchars($thesis['supervisors']) ?></dd>
+                <?php endif; ?>
+            </dl>
+        </section>
+
+        <section>
+            <h2>Contenu</h2>
+            <dl>
+                <?php if ($thesis['languages']): ?>
+                <dt>Langue(s)</dt><dd><?= htmlspecialchars($thesis['languages']) ?></dd>
+                <?php endif; ?>
+                <?php if ($thesis['formats']): ?>
+                <dt>Format(s)</dt><dd><?= htmlspecialchars($thesis['formats']) ?></dd>
+                <?php endif; ?>
+                <?php if ($thesis['keywords']): ?>
+                <dt>Mots-clés</dt><dd><?= htmlspecialchars($thesis['keywords']) ?></dd>
+                <?php endif; ?>
+                <?php if ($thesis['file_size_info']): ?>
+                <dt>Durée / Taille</dt><dd><?= htmlspecialchars($thesis['file_size_info']) ?></dd>
+                <?php endif; ?>
+                <?php if ($thesis['baiu_link']): ?>
+                <dt>Lien</dt><dd><a href="<?= htmlspecialchars($thesis['baiu_link']) ?>" target="_blank" rel="noopener"><?= htmlspecialchars($thesis['baiu_link']) ?></a></dd>
+                <?php endif; ?>
+            </dl>
+        </section>
+
+        <?php if (!empty($files)): ?>
+        <section>
+            <h2>Fichiers</h2>
+            <table>
+                <thead><tr><th scope="col">Type</th><th scope="col">Fichier</th><th scope="col">Taille</th><th scope="col">Date</th></tr></thead>
+                <tbody>
+                    <?php foreach ($files as $f): ?>
+                    <tr>
+                        <td><?= htmlspecialchars($f['file_type']) ?></td>
+                        <td><?= htmlspecialchars($f['file_name']) ?></td>
+                        <td><?= formatFileSize($f['file_size']) ?></td>
+                        <td><?= date('d/m/Y H:i', strtotime($f['uploaded_at'])) ?></td>
+                    </tr>
+                    <?php endforeach; ?>
+                </tbody>
+            </table>
+        </section>
+        <?php endif; ?>
+
+        <div class="admin-action-bar">
+            <a href="/admin/edit.php?id=<?= $thesisId ?>" class="admin-btn">Modifier</a>
+            <a href="/admin/add.php" class="admin-btn-secondary">Ajouter un autre TFE</a>
+            <a href="/admin/" class="admin-btn-secondary">Retour à la liste</a>
+        </div>
+
+    <?php else: ?>
+        <p class="admin-muted">Aucune donnée à afficher.</p>
+        <p><a href="/admin/add.php" class="admin-btn-secondary">Retour au formulaire</a></p>
+    <?php endif; ?>
+
+    <?php endif; ?>
+</main>