feat: dual upload system — direct file storage + PeerTube API integration

Adds a parallel PeerTube upload system behind a feature flag (disabled by default
until upload quota is granted). When disabled, the existing direct file upload
path works unchanged.

Files:
- src/PeerTubeService.php — credential storage (encrypted), OAuth2 token
  retrieval, multipart upload to /api/v1/videos/upload
- migrations/021_peertube_settings.sql — peertube_settings singleton table
  + peertube_upload_enabled site_setting (default 0)
- admin/actions/settings.php — peertube section handler
- admin/parametres.php / templates/admin/parametres.php — PeerTube UI section
- partage/fichiers-fragment.php — shows file inputs when enabled, TODO notice otherwise
- ThesisCreateController / ThesisEditController — handlePeerTubeUpload()
- tfe.php — PeerTube iframe embed detection
- AdminLogger — logPeerTubeUpdate()

app/templates/public/tfe.php

@@ -443,6 +443,7 @@
                     $isAudio   = in_array($ext, ['mp3','ogg','oga','wav','flac','aac','m4a'], true) || $fileType === 'audio';
                     $isPdf     = ($ext === 'pdf') || $fileType === 'main';
                     $isWebsite = ($fileType === 'website');
+                    $isPeerTube = ($isExternalUrl && str_contains($filePath, '/videos/watch/'));
                     $isOther   = !($isImage || $isVideo || $isAudio || $isPdf || $isWebsite);
 
                     $_vttPath = null;
@@ -485,6 +486,22 @@
                             <img src="<?= $mediaUrl ?>"
                                  alt="<?= htmlspecialchars($caption !== '' ? $caption : $data['title'] . ' — ' . ($data['authors'] ?? '')) ?>">
                         <?php elseif ($isVideo): ?>
+                            <?php if ($isPeerTube): ?>
+                            <iframe src="<?= $mediaUrl ?>embed"
+                                    width="100%" height="400px"
+                                    style="border:none"
+                                    title="<?= $fileName ?>"
+                                    sandbox="allow-same-origin allow-scripts"
+                                    allowfullscreen
+                                    loading="lazy">
+                            </iframe>
+                            <p class="tfe-pdf-fallback">
+                                <a href="<?= $mediaUrl ?>" target="_blank" rel="noopener">
+                                    Ouvrir dans PeerTube
+                                    <span class="sr-only">(ouvre dans un nouvel onglet)</span>
+                                </a>
+                            </p>
+                            <?php else: ?>
                             <video width="100%" controls>
                                 <source src="<?= $mediaUrl ?>" type="video/<?= htmlspecialchars($ext === 'mov' ? 'mp4' : $ext) ?>">
                                 <?php if ($_vttPath): ?>
@@ -493,7 +510,23 @@
                                        srclang="fr" label="Sous-titres" default>
                                 <?php endif; ?>
                             </video>
+                            <?php endif; ?>
                         <?php elseif ($isAudio): ?>
+                            <?php if ($isPeerTube): ?>
+                            <iframe src="<?= $mediaUrl ?>embed"
+                                    width="100%" height="170px"
+                                    style="border:none"
+                                    title="<?= $fileName ?>"
+                                    sandbox="allow-same-origin allow-scripts"
+                                    loading="lazy">
+                            </iframe>
+                            <p class="tfe-pdf-fallback">
+                                <a href="<?= $mediaUrl ?>" target="_blank" rel="noopener">
+                                    Ouvrir dans PeerTube
+                                    <span class="sr-only">(ouvre dans un nouvel onglet)</span>
+                                </a>
+                            </p>
+                            <?php else: ?>
                             <audio controls class="tfe-audio">
                                 <source src="<?= $mediaUrl ?>" type="audio/<?= htmlspecialchars(match($ext) {
                                     'mp3'        => 'mpeg',
@@ -506,6 +539,7 @@
                                 }) ?>">
                                 Votre navigateur ne supporte pas la lecture audio.
                             </audio>
+                            <?php endif; ?>
                         <?php else: /* other — download only */ ?>
                             <div class="tfe-download-file">
                                 <a href="<?= $mediaUrl ?>&download=1" class="tfe-download-link">