Add PDF validation in email script; add Nat_SubSubGroupSequence column

- Skip attachment if downloaded content is not a valid PDF (HTML error response)
- Add Nat_SubSubGroupSequence to nat_subsubgroup table (missing column
  referenced by sp_rpt_hasil_lab in SELECT and ORDER BY)

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

scripts/send_email.php

@@ -292,6 +292,11 @@ foreach ($rows as $row) {
             continue;
         }
 
+        if (substr($pdf, 0, 4) !== '%PDF') {
+            log_msg("  Not a PDF (got HTML/error response), skipping");
+            continue;
+        }
+
         $tmp = tempnam(sys_get_temp_dir(), 'ibl_email_') . '.pdf';
         file_put_contents($tmp, $pdf);
         $tmp_files[] = $tmp;

sql/manual_changes/2026-05-24-add-nat-subsubgroup-sequence-column.sql

@@ -0,0 +1,5 @@
+-- Add missing Nat_SubSubGroupSequence column to nat_subsubgroup
+-- Required by sp_rpt_hasil_lab which references this column in SELECT and ORDER BY
+
+ALTER TABLE nat_subsubgroup
+  ADD COLUMN Nat_SubSubGroupSequence char(2) NOT NULL DEFAULT '' AFTER Nat_SubSubGroupCode;