feat: P4 backend kvalita - SELECT * fix, overdue konsolidace, Validator

- SELECT * nahrazen explicitnimi sloupci ve 22 PHP souborech (69+ vyskytu)
- users-handlers.php: password_hash explicitne vyloucen z dotazu
- Overdue detekce presunuta do invoices.php routeru (1x pred dispatch misto 3x v handlerech)
- Validator.php: validacni helper s pravidly required, string, int, email, in, numeric
- PaginationHelper: PHPStan typy opraveny

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/includes/AttendanceHelpers.php

@@ -217,7 +217,9 @@ function enrichRecordsWithProjectLogs(PDO $pdo, array &$records): void
     if (!empty($recordIds)) {
         $placeholders = implode(',', array_fill(0, count($recordIds), '?'));
         $stmt = $pdo->prepare(
-            "SELECT * FROM attendance_project_logs WHERE attendance_id IN ($placeholders) ORDER BY started_at ASC"
+            "SELECT id, attendance_id, project_id, started_at, ended_at, hours, minutes
+            FROM attendance_project_logs
+            WHERE attendance_id IN ($placeholders) ORDER BY started_at ASC"
         );
         $stmt->execute($recordIds);
         foreach ($stmt->fetchAll() as $log) {