Backend of the sub-market template (spec agreed section by section with

the customer workflow in mind: the customer fills one XLSX per sub-market,
an importer builds the page).

- Frontend layout 21 'Sub-Market Page' in the existing
  BackendLayoutDataProvider: six zones, one per Figma section, emitted as
  colPos110..colPos160 - the JSON groups plus appearance.layout are the
  front-end contract (spec clause 7.17). A first attempt via page-TSconfig
  BackendLayouts was the wrong mechanism next to the provider and was
  removed again
- New Content Blocks vitec_markethero, vitec_marketintro,
  vitec_marketinsights (field bags, serialized unprefixed under data);
  the workflow section reuses intro-paragraph + vitec_card flip cards
- Stories gained quote/quote_person/quote_role (Testimonial tab),
  maintained once per story, emitted on every story card; usecaselist
  gained the layout value 'testimonials'
- New plugin vitec_productfeature: one referenced product as a full
  product card, serialisation shared with the product list (cObj made
  protected for the subclass)
- vitec_productlist gained hand-picked product selection: exactly the
  chosen products in the editor's order, category filter ignored,
  visibility filters kept - closes the long-standing single-select gap
- New CLI vitec:generate-submarket-workbooks: one protected customer
  XLSX per sub-market (9 main markets, 25 sub-markets from the Market
  category tree) - dropdowns filled live from the database, named ranges
  as the importer contract, hidden Meta sheet pinning submarket/group/
  record uid, soft character-limit warnings, asset URL fields

Verified end to end on Broadcast & Media: layout-21 payload with colPos110
carrying the hero element and its subline. Spec raised to v1.20.

packages/vitec/ContentBlocks/ContentElements/market-intro/assets/icon.svg

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="16" height="16">
+  <rect x="1.5" y="2.5" width="13" height="11" rx="1" fill="none" stroke="#000" stroke-width="1.2"/>
+  <text x="3.4" y="6.6" font-family="serif" font-weight="bold" font-size="6" fill="#000">¶</text>
+  <rect x="3" y="8" width="9" height="1" rx="0.2" fill="#000" opacity="0.4"/>
+  <rect x="3" y="9.6" width="7.5" height="1" rx="0.2" fill="#000" opacity="0.35"/>
+  <rect x="3" y="11.2" width="4" height="1.6" rx="0.3" fill="#000" opacity="0.55"/>
+</svg>