Sub-solution workbook pipeline on layout 5, fix element order in both importers

- New, deliberately separate pipeline for sub-solutions (markets and
  solutions must never break each other): generator
  vitec:generate-subsolution-workbooks (list from the page tree below
  /solutions, 39 workbooks, every sub-solution matched to its record),
  SubsolutionWorkbookImporter + CLI vitec:import-subsolution-workbooks,
  and a "Sub-Solutions" tab in the VITEC Import module with its own
  inbox migrations/subsolutions_xlsx_in/
- Targets the existing template 5 "Solution Detail" without changing
  it: hero element in colPos 1, the remaining sections in fixed order in
  colPos 0, found again by CType on re-import; existing empty sub-solution
  pages are switched to layout 5, missing ones created hidden;
  detail_page set on the solution record
- Workbook per the Figma "07 Solution Detail page": hero without video
  teaser, intro with headline and without learn-more/portfolio, extended
  icon list, own page-layout reference image
- Shared content elements: market hero/intro/insights relabelled
  "Market/Solution", market intro gains the optional intro_headline
  field (new column, requires extension:setup)
- Fix: DataHandler puts every NEW record with a positive pid at the top
  of its column, so pages built in one run came out reversed. Both
  importers now track the page order per colPos and write
  tt_content.sorting explicitly after the DataHandler run; re-applying
  repairs pages imported earlier (verified on the control-room
  sub-solution and sub-market page 443)
- migrations/fill_test_subsolution.php: realistic test content from
  vitec.com copy and images for the control-room sub-solution
- Docs section 5z

packages/vitec/ContentBlocks/ContentElements/market-hero/language/labels.xlf

@@ -1,8 +1,8 @@
-<?xml version="1.0" encoding="UTF-8"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <xliff version="1.2">
   <file source-language="en" datatype="plaintext" original="messages">
     <body>
-      <trans-unit id="title"><source>VITEC · Market Hero</source></trans-unit>
+      <trans-unit id="title"><source>VITEC · Market/Solution Hero</source></trans-unit>
       <trans-unit id="description"><source>Sub-market template, section 1: subline, CTA, background image, optional video teaser. The H1 is the page title.</source></trans-unit>
       <trans-unit id="subline.label"><source>Subline</source></trans-unit>
       <trans-unit id="subline.description"><source>Max ~90 characters visible (two lines in the design).</source></trans-unit>