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>

packages/vitec/Classes/Domain/Repository/EventRepository.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace Evomedien\Vitec\Domain\Repository;
+
+use TYPO3\CMS\Extbase\Persistence\QueryInterface;
+use TYPO3\CMS\Extbase\Persistence\QueryResultInterface;
+use TYPO3\CMS\Extbase\Persistence\Repository;
+
+/**
+ * The repository for Event
+ */
+class EventRepository extends Repository
+{
+    protected $defaultOrderings = [
+        'eventstart' => QueryInterface::ORDER_ASCENDING,
+    ];
+
+    /**
+     * All upcoming (or currently running) events, soonest first.
+     * "Upcoming" = event end (or start, when no end is set) is today or later.
+     */
+    public function findUpcoming(): QueryResultInterface
+    {
+        $todayMidnight = strtotime('today');
+
+        $query = $this->createQuery();
+        $query->getQuerySettings()->setRespectStoragePage(false);
+        $query->matching(
+            $query->logicalAnd(
+                $query->equals('hideonwebsite', 0),
+                $query->logicalOr(
+                    $query->greaterThanOrEqual('eventend', $todayMidnight),
+                    $query->logicalAnd(
+                        $query->equals('eventend', 0),
+                        $query->greaterThanOrEqual('eventstart', $todayMidnight)
+                    )
+                )
+            )
+        );
+        return $query->execute();
+    }
+
+    /**
+     * Past events, most recent first.
+     */
+    public function findPast(): QueryResultInterface
+    {
+        $todayMidnight = strtotime('today');
+
+        $query = $this->createQuery();
+        $query->getQuerySettings()->setRespectStoragePage(false);
+        $query->matching(
+            $query->logicalAnd(
+                $query->equals('hideonwebsite', 0),
+                $query->logicalOr(
+                    $query->logicalAnd(
+                        $query->greaterThan('eventend', 0),
+                        $query->lessThan('eventend', $todayMidnight)
+                    ),
+                    $query->logicalAnd(
+                        $query->equals('eventend', 0),
+                        $query->greaterThan('eventstart', 0),
+                        $query->lessThan('eventstart', $todayMidnight)
+                    )
+                )
+            )
+        );
+        $query->setOrderings(['eventstart' => QueryInterface::ORDER_DESCENDING]);
+        return $query->execute();
+    }
+}