Success stories: downloads and product sections become real plugins

- comparison report migrations/check_product_downloads.php (kept,
  read-only): download records vs. the delivered product workbooks -
  34 of 74 workbook products have a datasheet, the entire Datapath
  line has none in the pool (import came from vitec.com; queued for
  Joe), ~35 orphan datasheets belong to products without records;
  a vitec:link-product-downloads re-run added seven clean links
  (Artio x2, Diamond-H, the three TOUGH records, X-View)
- RTE resolution fixed at the root: ContentElementResolver and
  ContainerChildrenProcessor passed bodytext RAW into the payload, so
  t3:// links leaked unresolved; both now run RTE columns (bodytext,
  vitec_quote) through RteResolver::html()
- the imported "Download Success Story" RTE buttons carried the wrong
  link identifier (tx_vitec_download -> download, one-time migration
  fix_download_record_links.php) AND old-site uids - missing here or,
  worse, accidentally pointing at foreign PDFs. New
  vitec:convert-story-download-buttons replaces them with real
  vitec_downloadcard plugins: the download is resolved by STORY title
  (manual map for ISR / "Okada Manilla", exact-title fallback for
  suffixless PDFs like "Lord's Cricket Ground"); 29 converted, 4
  stories without a delivered PDF have their button hidden. New
  FlexForm layout "Success Story Download" (story_download) applied
  everywhere; the FE renders it as the previous centered button
- the ADIB "Featured Products" text section (the only one site-wide,
  verified by scan_story_headers.php) is now ONE vitec_productlist
  with hand-picked products via old-name aliases and the new FlexForm
  layout "Success Story Products" (story_products); the four text
  elements are deleted. vitec:convert-story-product-sections stays
  re-runnable for future imports
- the productlist envelope additionally carries "columns" (= number
  of products, capped at 4) so the story grid renders as many columns
  as it has products - additive key, available to every product list;
  and hand-picked lists now ship successStories as an empty array (the
  empty category selection used to aggregate stories over the WHOLE
  tree, leaking story cards into the section)
- the story downloadcards carry header "Downloads" (set on convert
  and backfilled): the front end builds the story anchor nav from
  element headers, so the section now appears there
- diagnosis scripts kept: check_download_record, check_story_elements,
  scan_story_headers; verified live on the ADIB payload (structured
  download object, productlist [5,18,6], texts 10 -> 5)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

migrations/scan_story_headers.php

@@ -0,0 +1,29 @@
+<?php
+declare(strict_types=1);
+// Scan: all text-element headers inside usecase content, grouped. READ-ONLY.
+error_reporting(E_ALL); ini_set('display_errors', '1');
+$root = null; $dir = __DIR__;
+for ($i = 0; $i < 5; $i++) { if (is_file($dir . '/config/system/settings.php')) { $root = $dir; break; } $dir = dirname($dir); }
+if ($root === null) { exit("no root\n"); }
+$db = (require $root . '/config/system/settings.php')['DB']['Connections']['Default'];
+$pdo = new PDO(sprintf('mysql:host=%s;port=%s;dbname=%s;charset=utf8mb4', $db['host'] ?? 'localhost', $db['port'] ?? 3306, $db['dbname'] ?? ''), $db['user'] ?? '', $db['password'] ?? '', [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC]);
+echo "=== Header von text-Elementen in Story-Content (gruppiert) ===\n";
+foreach ($pdo->query("SELECT TRIM(header) h, COUNT(*) c FROM tt_content WHERE deleted = 0 AND tx_vitec_usecase_content > 0 AND CType = 'text' AND TRIM(COALESCE(header,'')) <> '' GROUP BY TRIM(header) ORDER BY c DESC, h") as $r) {
+    printf("  %3d x %s\n", $r['c'], $r['h']);
+}
+echo "\n=== CTypes in Story-Content gesamt ===\n";
+foreach ($pdo->query("SELECT CType, COUNT(*) c FROM tt_content WHERE deleted = 0 AND tx_vitec_usecase_content > 0 GROUP BY CType ORDER BY c DESC") as $r) {
+    printf("  %3d x %s\n", $r['c'], $r['CType']);
+}
+
+echo "\n=== Header von Kind-Elementen in Story-vitec_columns ===\n";
+foreach ($pdo->query(
+    "SELECT TRIM(c.header) h, c.CType, COUNT(*) n FROM tt_content c
+     WHERE c.deleted = 0 AND TRIM(COALESCE(c.header,'')) <> ''
+       AND c.tx_container_parent IN (
+           SELECT p.uid FROM tt_content p
+           WHERE p.deleted = 0 AND p.tx_vitec_usecase_content > 0 AND p.CType = 'vitec_columns')
+     GROUP BY TRIM(c.header), c.CType ORDER BY n DESC, h"
+) as $r) {
+    printf("  %3d x %-14s %s\n", $r['n'], $r['CType'], $r['h']);
+}