feat: obfuscate all email addresses and mailto links as HTML entities

Added EmailObfuscator class (src/EmailObfuscator.php) that converts
email addresses to HTML decimal entities (e.g. foo@...)
so browsers render them correctly but bots and scrapers see gibberish.

Methods:
- email($addr): obfuscate for display in HTML content
- mailto($addr): return obfuscated mailto: href
- obfuscateHtml($html): post-process rendered HTML to obfuscate all
  mailto: links (used after Parsedown/Markdown rendering)

Applied to:
- partage/index.php: mailto link at top + error scenarios via _flash_contact
  flag rendered in form.php (outside htmlspecialchars to avoid double-escape)
- admin/acces.php: request email mailto links
- admin/file-access.php: request email mailto links
- public/about.php: contact email mailto links
- public/tfe.php: author contact mailto links
- AboutController: Parsedown output post-processing
- LicenceController: Parsedown output post-processing
- Dispatcher::render(): require_once EmailObfuscator for all public views

Also fixed _flash_contact session flag in form.php partial to show
contact email line on share link validation errors (separate from
flash_error/warning to bypass htmlspecialchars double-escaping).

app/templates/admin/acces.php

@@ -181,6 +181,19 @@
 +%%%%%%% diff from: somsyvxz 249f7943 "Bulk bar anti-shift, tags icons, AP no-wrap, credits reorder" (rebased revision)
 +\\\\\\\        to: kvyyvksn c5873f06 "fix: add help email, preserve file names on validation error, license fix" (rebased revision)
 ++                        $linkName = $link['name'] ?? '';
+++                        $linkExpiresVal = $link['expires_at'] ? date('Y-m-d\TH:i', strtotime($link['expires_at'])) : '';
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% diff from: kvyyvksn c5873f06 "fix: add help email, preserve file names on validation error, license fix" (rebased revision)
+\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\        to: somsyvxz 249f7943 "Bulk bar anti-shift, tags icons, AP no-wrap, credits reorder" (rebased revision)
+-                        $linkName = $link['name'] ?? '';
+-                        $linkExpiresVal = $link['expires_at'] ? date('Y-m-d\TH:i', strtotime($link['expires_at'])) : '';
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% diff from: somsyvxz 14a3cd10 "Bulk bar anti-shift, tags icons, AP no-wrap, credits reorder" (rebase destination)
+\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\        to: roqtyzln d714ae9b "feat: obfuscate all email addresses and mailto links as HTML entities" (rebased revision)
+                         $linkName = $link['name'] ?? '';
+                         $linkExpiresVal = $link['expires_at'] ? date('Y-m-d\TH:i', strtotime($link['expires_at'])) : '';
+                         $linkLockedYear = $link['locked_year'] ?? null;
++%%%%%%% diff from: somsyvxz 249f7943 "Bulk bar anti-shift, tags icons, AP no-wrap, credits reorder" (rebased revision)
++\\\\\\\        to: roqtyzln 34d91340 "feat: obfuscate all email addresses and mailto links as HTML entities" (rebased revision)
+++                        $linkName = $link['name'] ?? '';
 ++                        $linkExpiresVal = $link['expires_at'] ? date('Y-m-d\TH:i', strtotime($link['expires_at'])) : '';
                     ?>
                     <tr class="admin-table-row" onclick="event.stopPropagation(); window.open('/partage/<?= urlencode($link['slug']) ?>', '_blank')" style="cursor:pointer">
@@ -367,9 +380,7 @@
                             <div class="access-req-card__info">
                                 <div>
                                     <strong>Email :</strong>
-                                    <a href="mailto:<?= htmlspecialchars($req['email']) ?>">
-                                        <?= htmlspecialchars($req['email']) ?>
-                                    </a>
+                                    <a href="<?= EmailObfuscator::mailto($req['email']) ?>"><?= htmlspecialchars($req['email']) ?></a>
                                 </div>
                                 <div>
                                     <strong>Date :</strong>