Add evo_megamenu_json extension and seed the megamenu

- new project-neutral extension evo_megamenu_json (Evomedien): a Megamenu
  plugin holding entries, columns, items, teaser cards and a featured slot
  as nested records; presentation settings travel with the payload so the
  front end reads behaviour instead of hard-coding it; published as
  page.10.fields.megaMenu, driven by the site settings megamenu.contentUid
  and megamenu.storagePid
- vitec:seed-megamenu fills one element from the live structure: 5 entries,
  26 columns, 95 items, 4 story cards; items without a page yet are flagged
  pending so the front end falls back to the column link
- vitec:debug-sets prints the resolved site set order
- read-only diagnostics: check_megamenu_schema.php, check_typoscript_templates.php
- docs: schema updates run via extension:setup (database:updateschema no
  longer exists in v14), and a JSON Accept header activates headless-mixed,
  which strips every set-added page field

packages/evo_megamenu_json/composer.json

@@ -0,0 +1,24 @@
+{
+    "name": "evomedien/evo-megamenu-json",
+    "type": "typo3-cms-extension",
+    "description": "Editable megamenu for headless TYPO3 - one plugin fills columns, teaser cards and a featured slot, delivered as JSON",
+    "version": "1.0.0",
+    "authors": [],
+    "license": "GPL-2.0-or-later",
+    "require": {
+        "typo3/cms-core": "^13.4 || ^14.0"
+    },
+    "suggest": {
+        "friendsoftypo3/headless": "Renders the plugin inside the headless JSON envelope and exposes the menu at page level"
+    },
+    "autoload": {
+        "psr-4": {
+            "Evomedien\\EvoMegamenuJson\\": "Classes"
+        }
+    },
+    "extra": {
+        "typo3/cms": {
+            "extension-key": "evo_megamenu_json"
+        }
+    }
+}