tfe: rework desktop layout to 35/65 flex columns, independent scrolling, no horizontal overflow

Switched from grid to flex for two-column layout
Left column (flex: 0 0 35%): author, title, meta, synopsis — scrolls independently  
Right column (flex: 1): files/media — scrolls independently
Added .tfe-file-iframe class to PDF/website iframes, scoped width/height constraints
All media gets width:100% + max-width:100% to prevent overflow
Mobile (<900px): reverts to single-column page-level scrolling

app/templates/public/tfe.php

@@ -1,8 +1,10 @@
 <main class="tfe-main" id="main-content">
     <article class="tfe-layout">
 
-        <!-- ROW 1: Author above Title -->
-        <div class="tfe-header-row">
+        <!-- Two-column layout: left 35% (info), right 65% (files) -->
+        <div class="tfe-content-row">
+            <div class="tfe-left-column">
+
             <p class="tfe-author"><?= htmlspecialchars(
                 $data["authors"] ?? "Auteur inconnu",
             ) ?></p>
@@ -13,10 +15,7 @@
                     – <?= htmlspecialchars($data["subtitle"]) ?>
                 <?php endif; ?>
             </h1>
-        </div>
 
-        <!-- ROW 2: Two columns — meta left, synopsis right -->
-        <div class="tfe-content-row">
             <div class="tfe-meta">
                 <?php if (!empty($data["orientation"])): ?>
                 <p class="tfe-meta-item">
@@ -272,10 +271,11 @@
                 <div class="tfe-synopsis-text tfe-synopsis-empty"></div>
                 <?php endif; ?>
             </div>
-        </div>
 
-        <!-- ROW 3: All files — flex container -->
-        <div class="tfe-files">
+            </div><!-- /tfe-left-column -->
+
+            <div class="tfe-right-column">
+            <div class="tfe-files">
             <?php $_videoIndex = 0; ?>
             <?php if ($isInterdit): ?>
                 <p class="tfe-restricted">
@@ -377,14 +377,12 @@
                     <div class="tfe-file-item">
                         <?php if ($isPdf): ?>
                             <iframe src="<?= $mediaUrl ?>#toolbar=0&navpanes=0"
-                                    width="100%" height="700px"
-                                    style="border:none"
+                                    class="tfe-file-iframe"
                                     title="<?= $fileName ?>">
                             </iframe>
                         <?php elseif ($isWebsite): ?>
                             <iframe src="<?= $mediaUrl ?>"
-                                    width="100%" height="700px"
-                                    style="border:none"
+                                    class="tfe-file-iframe"
                                     title="<?= $fileName ?>"
                                     sandbox="allow-scripts allow-same-origin"
                                     loading="lazy">
@@ -452,6 +450,10 @@
             <?php else: ?>
                 <p class="tfe-no-files">Aucun fichier disponible pour ce TFE.</p>
             <?php endif; ?>
+            </div>
+
+            </div><!-- /tfe-right-column -->
+
         </div>
 
     </article>