Add an AI slop verdict that downrates the author's future articles

A fourth explicit verdict, "AI slop" (Vote::Slop, label `slop`), joins the
rating widget on the web, the EPUB footer links, the /r/ confirmation page,
the CLI, imports and the dashboard filters. It counts as a full negative
(curation.feedback.slop_value, -1.0) in the neighbour and affinity signals.

Beyond that, each run loads the authors whose current verdict is slop, with
no lookback, and multiplies the preliminary blend and the utility of every
candidate by that author by 1 - curation.ranking.slop_author_penalty (0.75),
so they sink before triage. The flag is recorded in signals_json, shown by
`explain` and the dashboard signals table, and the confirmation names the
author (or says no author is known, in which case only the rating applies).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VXYGBPoHZSDSfE5WcJ9bvj

src/web/issue.rs

@@ -2768,6 +2768,88 @@ mod tests {
         assert_eq!(down, "not_for_me");
     }
 
+    #[tokio::test]
+    async fn slop_verdict_is_stored_under_its_own_label_and_names_the_author() {
+        let (_dir, db, source) = seeded_issue(true).await;
+        let article_id = source.lineup.picks[0].article.id;
+        sqlx::query("UPDATE articles SET author = ? WHERE id = ?")
+            .bind("Content Farm")
+            .bind(article_id)
+            .execute(db.pool())
+            .await
+            .unwrap();
+        crate::web::users::add(&db, "admin", "correct horse battery", true)
+            .await
+            .unwrap();
+        let app = crate::server::router(crate::server::AppState::new(
+            db.clone(),
+            crate::config::Config::default(),
+            None,
+        ));
+        let admin_cookie = login_cookie(&app, "admin", "correct horse battery").await;
+
+        let json = app
+            .clone()
+            .oneshot(
+                Request::builder()
+                    .method(Method::POST)
+                    .uri("/rate")
+                    .header(header::COOKIE, &admin_cookie)
+                    .header(header::CONTENT_TYPE, "application/json")
+                    .header(header::ACCEPT, "application/json")
+                    .header("sec-fetch-site", "same-origin")
+                    .body(Body::from(
+                        json!({"article_id": article_id, "label": "slop"}).to_string(),
+                    ))
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(json.status(), StatusCode::OK);
+        let body: serde_json::Value = serde_json::from_str(&response_text(json).await).unwrap();
+        assert_eq!(body["label"], "slop");
+        let stored = sqlx::query("SELECT label, value FROM rating_events ORDER BY id DESC LIMIT 1")
+            .fetch_one(db.pool())
+            .await
+            .unwrap();
+        assert_eq!(stored.get::<String, _>("label"), "slop");
+        assert_eq!(stored.get::<f64, _>("value"), -1.0);
+        assert_eq!(db.slop_authors().await.unwrap(), ["Content Farm"]);
+
+        let redirected = app
+            .clone()
+            .oneshot(
+                Request::builder()
+                    .method(Method::POST)
+                    .uri("/rate")
+                    .header(header::COOKIE, &admin_cookie)
+                    .header(header::CONTENT_TYPE, "application/x-www-form-urlencoded")
+                    .header("sec-fetch-site", "same-origin")
+                    .body(Body::from(format!(
+                        "article_id={article_id}&label=slop&next=%2Fissues%2F{}",
+                        source.meta.date
+                    )))
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(redirected.status(), StatusCode::SEE_OTHER);
+        let page = app
+            .oneshot(
+                Request::builder()
+                    .uri(format!("/issues/{}", source.meta.date))
+                    .header(header::COOKIE, &admin_cookie)
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .unwrap();
+        let html = response_text(page).await;
+        assert!(html.contains("Future articles by Content Farm will rank much lower"));
+        assert!(html.contains(r#"data-label="slop" title="Report as AI slop"#));
+        assert!(html.contains(r#"value="slop" data-label="slop" title="Report as AI slop: a strong Not for me, and future articles by this author rank much lower" class="active" aria-pressed="true""#));
+    }
+
     #[tokio::test]
     async fn toc_numbers_chapters_across_sections_and_tracks_the_reader() {
         let (_dir, db, source) = seeded_issue(true).await;