Checkpoint: headless JSON architecture documented + cleanup (Stufe 1+2)

Restore point before Stufe 3 (central resolver-service refactoring).

Includes this session's work:
- Success Story (usecase) rebuild: new fields/tabs, UsecaseSerializer,
  thin List/Show renderers, MM relations, inline content elements.
- vitec_columns content block (two-column layout with per-item content)
  incl. unified header section; special-cased JSON resolution.
- Container per-column flex (items[].config align/justify) + gap on parent.
- Unified header section across CEs/plugins/containers; header fields in JSON.
- ISO-style architecture spec: Documentation/Headless-JSON-Architecture.md.
- Cleanup: removed local scratch + verified .bak backups.
- Fixes: B-6 (undefined thumbnail variable in Downloadcardcollection image
  resolver), B-7 (unsatisfiable legacy CType OR branch in Downloadcard/Datasheets).

Rollback: git reset --hard snapshot-2026-07-09-pre-stufe3

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

config/sites/vitec/config.yaml

@@ -15,6 +15,11 @@ dependencies:
   - vitec/card
   - vitec/intro-paragraph
   - vitec/video
+  - vitec/faq
+  - georgringer/news
+  - georgringer/news-sitemap
+  - georgringer/news-recordlinks
+  - vitec/columns
 frontendBase: ''
 headless: 1
 languages:
@@ -49,4 +54,19 @@ routeEnhancers:
         tableName: tx_vitec_domain_model_product
         routeFieldName: slug
         routeValuePrefix: ''
+  NewsDetail:
+    type: Extbase
+    limitToPages:
+      - 21
+    extension: News
+    plugin: Pi1
+    routes:
+      - routePath: '/{news-title}'
+        _controller: 'News::detail'
+        _arguments:
+          news-title: news
+    defaultController: 'News::detail'
+    aspects:
+      news-title:
+        type: NewsTitle
 websiteTitle: ''