Add <meta name=description> to all public pages; improve page titles

- templates/public/head.php: emit <meta name="description"> when $metaDescription is set
- index.php: title → 'Posterg – Mémoires de l\'ERG'; description = site blurb
- tfe.php: title → '[Titre] – [Auteur] – Posterg'; description = synopsis excerpt (strip_tags, truncate 160)
- search.php: description = répertoire purpose blurb
- apropos.php: description = about-page blurb
- licence.php: description = licences blurb

Fixes WCAG 2.4.2 (Page Titled) for index.php and tfe.php.
All descriptions properly htmlspecialchars-escaped at render time.

TODO.md

@@ -534,7 +534,7 @@ Goal: rename the tables and column to the canonical M2M pattern (`tags`, `thesis
       `<form>` and no `<label>` for the input (only a placeholder). Add `aria-label="Recherche"` to
       the `<form>` element; also add `role="search"`, a visually-hidden `<label>` linked via `for`/`id`.
 
-- [ ] **No `<meta name="description">` on any public page** - all public pages omit the description
+- [x] **No `<meta name="description">` on any public page** - all public pages omit the description
       meta tag (the dead `templates/head.php` had `content=""`). Add per-page descriptions:
       site blurb for `index.php`, synopsis excerpt for `tfe.php`, page content intro for
       `apropos.php`/`licence.php`. Necessary for search indexing and link preview cards.
@@ -1100,7 +1100,7 @@ Current state: **zero ARIA attributes, zero skip links, zero focus-visible style
 
 #### 2.4.2 Page titled
 
-- [ ] **`index.php` `<title>` is just "Posterg"** - no description of the page content.
+- [x] **`index.php` `<title>` is just "Posterg"** - no description of the page content.
       Change to "Posterg - Mémoires de l'ERG" or similar. Each page title should be unique and
       descriptive first: "Répertoire - Posterg", "À Propos - Posterg" (already good), but
       `tfe.php` uses just the thesis title without author: add author - "[Titre] - [Auteur] - Posterg".

public/apropos.php

@@ -25,6 +25,7 @@ $pd = new Parsedown();
 $pd->setSafeMode(true);
 $aboutHtml = $pd->text($rawContent);
 $pageTitle = 'À Propos – Posterg';
+$metaDescription = 'À propos de Posterg, le répertoire des mémoires de fin d\'études de l\'erg – École de Recherches Graphiques de Bruxelles.';
 $extraCss = ['assets/apropos.css'];
 ?>
 <?php include APP_ROOT . '/templates/public/head.php'; ?>

public/index.php

@@ -50,7 +50,8 @@ try {
 }
 
 $currentNav = '';
-$pageTitle = 'Posterg';
+$pageTitle = 'Posterg – Mémoires de l\'ERG';
+$metaDescription = 'Posterg répertorie et valorise les mémoires de fin d\'études (TFE) de l\'erg – École de Recherches Graphiques de Bruxelles.';
 $extraCss = ['assets/main.css'];
 ?>
 <?php include APP_ROOT . '/templates/public/head.php'; ?>

public/licence.php

@@ -21,6 +21,7 @@ $pd->setSafeMode(true);
 $html = $pd->text($content);
 
 $pageTitle = $licencePageTitle . ' – Posterg';
+$metaDescription = 'Informations sur les licences d\'utilisation des mémoires publiés sur Posterg, le répertoire des TFE de l\'erg.';
 $extraCss = ['assets/apropos.css'];
 ?>
 <?php include APP_ROOT . '/templates/public/head.php'; ?>

public/search.php

@@ -62,6 +62,7 @@ try {
 $currentNav = 'repertoire';
 $searchBarValue = $_GET['query'] ?? '';
 $pageTitle = 'Répertoire – Posterg';
+$metaDescription = 'Parcourez le répertoire des mémoires de fin d\'études (TFE) de l\'erg – École de Recherches Graphiques de Bruxelles. Recherche par année, orientation, atelier et mots-clés.';
 $extraCss = ['assets/search.css'];
 ?>
 <?php include APP_ROOT . '/templates/public/head.php'; ?>

public/tfe.php

@@ -17,7 +17,14 @@ if (isset($_GET['id'])) {
 }
 
 $currentNav = '';
-$pageTitle = $data['title'] . ' – Posterg';
+$_tfeAuthor = $data['authors'] ?? '';
+$pageTitle = $data['title'] . (!empty($_tfeAuthor) ? ' – ' . $_tfeAuthor : '') . ' – Posterg';
+// Build meta description: strip markdown/HTML from synopsis, truncate to ~160 chars
+$_synopsisRaw = strip_tags($data['synopsis'] ?? '');
+$metaDescription = mb_strlen($_synopsisRaw) > 160
+    ? mb_substr($_synopsisRaw, 0, 157) . '…'
+    : (empty($_synopsisRaw) ? 'Mémoire de fin d\'études – Posterg, répertoire des TFE de l\'erg.' : $_synopsisRaw);
+unset($_tfeAuthor, $_synopsisRaw);
 $extraCss = ['assets/tfe.css'];
 ?>
 <?php include APP_ROOT . '/templates/public/head.php'; ?>

templates/public/head.php

@@ -4,6 +4,9 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title><?= htmlspecialchars($pageTitle ?? 'Posterg') ?></title>
+    <?php if (!empty($metaDescription)): ?>
+    <meta name="description" content="<?= htmlspecialchars($metaDescription) ?>">
+    <?php endif; ?>
     <link rel="icon" type="image/svg+xml" href="/assets/admin_favicon.svg">
     <link rel="stylesheet" href="assets/modern-normalize.min.css">
     <link rel="stylesheet" href="assets/common.css">