User feedback + expanded privacy-respecting admin stats

Feedback:
- feedback table; POST /api/feedback (anonymous-ok, optional category/email,
  honeypot + per-day flood cap) stores + emails the admin; GET /api/admin/feedback.
- Shared feedback store + FeedbackModal; a speech-bubble opens it from the desktop
  header, the mobile top bar (logo moves left), the footer, and /account. Feedback
  section in /admin.

Stats (additive, same privacy model — no IP/UA/referrer/raw terms):
- Event vocab: summary_viewed (fired on /a load), full_story (card → source),
  not_today/less_like_this/hide_topic, replace_used/replace_none, paywall_replace,
  paywalled_source_open. Card title/image opens /a (no double-count); history
  records via keepalive so it survives the nav.
- Dashboard: Accounts card (counts only), reading funnel (summary→source rate),
  emotional-mix & friction, paywall, returning-visitor buckets. (Health metrics
  deferred to a future monitoring dashboard.) 131 tests pass.

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

goodnews/share.py

@@ -162,6 +162,15 @@ def render_share_page(article: dict, base_url: str, summary: str | None = None)
       </div>
     </article>
   </main>
+  <script>
+(function(){{
+  try{{
+    var v=localStorage.getItem('goodnews:visitor')||'';
+    var b=JSON.stringify({{kind:'summary_viewed',article_id:{aid},visitor:v}});
+    if(navigator.sendBeacon) navigator.sendBeacon('/api/events', new Blob([b],{{type:'application/json'}}));
+  }}catch(e){{}}
+}})();
+</script>
   {src_click}
   <script>
 (function(){{