feat: tag management tests, maintenance mode polish, répertoire pagination fix

- tests/Unit/DatabaseTest.php: tests 5-7 for findOrCreateTag round-trip, getUsedTags column, alias
- tests/Integration/SearchTest.php: tests 4-6 for tag subquery, full-text query, count consistency
- Database: getAllPublishedTheses() bypasses 100-row search cap for student index
- search.php: uses getAllPublishedTheses() for étudiantes column; all tests pass

src/Database.php

@@ -402,6 +402,17 @@ class Database {
     /**
      * Get all available years from published theses
      */
+    /**
+     * Return ALL published theses (no cap) — for internal use (student index).
+     * Not exposed to user-controlled input.
+     */
+    public function getAllPublishedTheses(): array {
+        $stmt = $this->pdo->query(
+            "SELECT vp.* FROM v_theses_public vp ORDER BY vp.year DESC, vp.title ASC"
+        );
+        return $stmt->fetchAll();
+    }
+
     public function getAvailableYears() {
         $sql = "SELECT DISTINCT year FROM theses WHERE is_published = 1 ORDER BY year DESC";
         $stmt = $this->pdo->query($sql);