Success-story migration + new plugins + JSON/UX polish

- Success Stories: full migration from old site (48/48, audited),
  markets n:n, quotation content block, columns content block,
  pretty SEO detail URLs via SuccessStoryPathRewrite middleware,
  list/detail split (list page 4 / story page), detailUrl/backUrl
- New plugins: VITEC Locations (grid/list/map + RTE map text),
  VITEC Customer Logos (color/bw logic, only-show-selected),
  VITEC Card (one plugin for product/story/market/solution
  with reloading FlexForm + custom backend preview renderer)
- Eventlist: layout dropdown (list/grid/teaserbar) in settings
- Hero section CB: Images/Video tabs, background video + overlay
- Product JSON: full category rootline (parents), fixed missing
  ConnectionPool import (all-products crash), category tree map
- Backend preview CSS: container-query responsive (narrow columns)
- Docs: ISO architecture spec, root + extension READMEs

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

public/_frontend/index.html

@@ -25,8 +25,8 @@
     <link rel="preconnect" href="https://fonts.googleapis.com" />
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
     <title>VITEC</title>
-    <script type="module" crossorigin src="/_frontend/assets/index-7LYai_r-.js"></script>
-    <link rel="stylesheet" crossorigin href="/_frontend/assets/index-CQZZ8YAR.css">
+    <script type="module" crossorigin src="/_frontend/assets/index-CM0zIqrs.js"></script>
+    <link rel="stylesheet" crossorigin href="/_frontend/assets/index-B6-rfpgz.css">
   </head>
   <body>
     <div id="page"></div>␍