Fix frontend CSRF, clean reader URLs, and review findings

CSRF / actions:
- List action forms now send both REQUEST_TOKEN (Contao gate) and _token
  (Symfony, validated via isCsrfTokenValid) — mirrors the editor; fixes
  the 400/500 "Ungültiger CSRF-Token" on publish/toggle/duplicate/delete

Public reader / URLs:
- Reader & results read auto_item via Input::get (marks the route param used)
  so clean path URLs /<page>/<alias> no longer 404
- List controller generates path URLs via ['parameters' => '/'.$alias]
- Allow re-participation in the same session after a 60s cooldown

Review fixes:
- Results: merge answer snapshots by questionId+type (no more split cards on
  label edits); seed "Vielleicht" when allowMaybe so screen matches Excel
- Reader: replace generic answer hint with per-option "weiter zu Frage X"
  only when a jump is configured; strip HTML tags from survey description
- PDF: render free-text frequency summary; drop duplicate "Minimum" label
- Drag-sort: bundle SortableJS locally, drop the duplicated inline sort CSS/JS
  from _survey_assets, throttle the backend MutationObserver
- Backend: move hardcoded tl_survey operation labels to TL_LANG (de+en)
- Remove dead code: SurveyEditorVoter, SurveyPermissionService,
  categoryFilter/categorySummary + helpers, orphaned publishSurvey lang key

Reader layout:
- max-width 1000px (other views keep 1400px); back/next buttons fill the
  width as equal, card-sized halves; sort handle icon offset tweak

Docs: update AI_HANDOVER (dual-token CSRF, clean URLs) and README

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

contao/templates/frontend/show_survey.html.twig

@@ -5,7 +5,7 @@
 
 {% set moduleHeadline = (headline is iterable ? headline.text|default('') : headline|default(''))|striptags|trim %}
 
-<section class="survey-shell survey-grid">
+<section class="survey-shell survey-shell--reader survey-grid">
     {% if moduleHeadline %}
         <header><h2>{{ moduleHeadline }}</h2></header>
     {% endif %}
@@ -63,7 +63,10 @@
                             {% for child in surveyForm.answer %}
                                 <label class="survey-card" style="cursor: pointer;">
                                     <div class="survey-meta"><strong>{{ child.vars.label|striptags|trim }}</strong>{{ form_widget(child) }}</div>
-                                    <div>{{ 'survey.survey.answer_flow_hint'|trans }}</div>
+                                    {% set jumpHint = jumpHints|default({})[child.vars.value]|default(null) %}
+                                    {% if jumpHint %}
+                                        <div class="survey-jump-hint">{{ 'survey.survey.jump_to'|trans({'%position%': jumpHint.position, '%label%': jumpHint.label|striptags|trim}) }}</div>
+                                    {% endif %}
                                 </label>
                             {% endfor %}
                         </div>