fe_comment: Feedback Overview content element in the page JSON

- New content element "Feedback Overview" (CType fecomment_overview):
  the current FE user's feedback state under content.feedbackOverview,
  so the overview page renders like any other page instead of a
  front-end special case
- Rendered as USER_INT inside the cached page JSON (EXT:headless replaces
  the field per request): data is per user, visitors without a session
  get {"allowed": false} - verified that nothing leaks from the cache
- One implementation for both consumers: the new FeedbackState service
  builds the state payload; the API middleware delegates to it
- State payload (API and element) gained canSubmit and actions (all
  write endpoints with method and URL), so the front end needs no
  hard-coded endpoints for the submit button below the ticket list
- New site set evomedien/fe-comment carries the TypoScript, added to the
  site configuration; icon fecomment-overview

packages/fe_comment/Configuration/Sets/FeComment/setup.typoscript

@@ -0,0 +1,15 @@
+# "Feedback Overview" content element as headless JSON (2026-10-09):
+# content.feedbackOverview = the payload of GET /api/fe-comment/state.
+# USER_INT on purpose - the data is per FE user; EXT:headless caches the page
+# and replaces only this field on every request.
+tt_content.fecomment_overview < lib.contentElementWithHeader
+tt_content.fecomment_overview {
+    fields {
+        content {
+            fields {
+                feedbackOverview = USER_INT
+                feedbackOverview.userFunc = Evomedien\FeComment\UserFunc\OverviewJsonRenderer->render
+            }
+        }
+    }
+}