feat: admin tag management, maintenance mode, TFE visibility states

Tags admin:
- Database: getAllTagsWithCount(), renameTag(), mergeTag(), deleteTag()
- public/admin/tags.php: table with inline rename/merge/delete forms, CSRF-guarded
- public/admin/actions/tag.php: routes on action=rename|merge|delete
- templates/admin/head.php: 'Mots-clés' nav link
- admin.css: admin-inline-form, admin-btn--sm/warning/danger variants

Maintenance mode:
- config/bootstrap.php: gate on MAINTENANCE_FLAG file; admin/ and maintenance.php exempt
- public/maintenance.php: 503 dark minimal page
- public/admin/actions/maintenance.php: enable/disable toggle
- public/admin/index.php: status bar with toggle button
- admin.css: admin-maintenance-bar styles

TFE Visibility (Libre/Interne/Interdit via existing access_type_id):
- migration 002_add_visibility.sql: seeds access_types if missing
- Database: setVisibility(), bulkSetVisibility(), getAccessTypes()
- public/media.php: blocks thesis files for access_type_id=3
- public/tfe.php: shows access_type, context_note; hides file panel for Interdit
- public/admin/edit.php: access_type_id select + context_note textarea; saves both
- public/admin/index.php: three-state badge (Libre/Interne/Interdit) per row
- public/admin/actions/visibility.php: single + bulk visibility action handler
- admin.css: status-access badge variants

public/tfe.php

@@ -128,6 +128,13 @@ $currentNav = '';
                     </div>
                     <?php endif; ?>
 
+                    <?php if (!empty($data['access_type'])): ?>
+                    <div class="tfe-meta-item">
+                        <span class="label">Accès :</span>
+                        <span class="value"><?= htmlspecialchars($data['access_type']) ?></span>
+                    </div>
+                    <?php endif; ?>
+
                     <?php if (!empty($data['license_type'])): ?>
                     <div class="tfe-meta-item">
                         <span class="label">Licence :</span>
@@ -135,6 +142,13 @@ $currentNav = '';
                     </div>
                     <?php endif; ?>
 
+                    <?php if (!empty($data['context_note'])): ?>
+                    <div class="tfe-meta-item" style="align-items:start;">
+                        <span class="label">Note :</span>
+                        <span class="value" style="font-style:italic;"><?= nl2br(htmlspecialchars($data['context_note'])) ?></span>
+                    </div>
+                    <?php endif; ?>
+
                     <?php if (!empty($data['baiu_link'])): ?>
                     <div class="tfe-meta-item">
                         <span class="label">Contact :</span>
@@ -162,7 +176,24 @@ $currentNav = '';
 
             <!-- RIGHT: media -->
             <div class="tfe-right">
-                <?php if (!empty($data['files'])): ?>
+                <?php
+                    // Determine effective access: need raw access_type_id
+                    // The view exposes 'access_type' (name string). Fetch raw id for gate.
+                    $accessTypeId = null;
+                    try {
+                        $accessStmt = $db->getConnection()->prepare(
+                            "SELECT access_type_id FROM theses WHERE id = ?"
+                        );
+                        $accessStmt->execute([$thesisId]);
+                        $accessTypeId = (int)($accessStmt->fetchColumn() ?? 1);
+                    } catch (\Throwable $e) {}
+                    $isInterdit = ($accessTypeId === 3);
+                ?>
+                <?php if ($isInterdit): ?>
+                    <p class="tfe-no-files" style="color:#999;font-style:italic;">
+                        Ce TFE n'est pas disponible en ligne.
+                    </p>
+                <?php elseif (!empty($data['files'])): ?>
                     <?php foreach ($data['files'] as $file): ?>
                         <?php $ext = strtolower(pathinfo($file['file_path'], PATHINFO_EXTENSION)); ?>
                         <div class="tfe-media-block">
@@ -184,7 +215,7 @@ $currentNav = '';
                     <?php endforeach; ?>
                 <?php else: ?>
                     <p class="tfe-no-files">Aucun fichier disponible pour ce TFE.</p>
-                <?php endif; ?>
+                <?php endif; // end !$isInterdit ?>
             </div>
 
         </div>