feat(mangas): content-warning filter on search + deduped banner on detail

Surfaces the analysis worker's NSFW moderation at the manga level:

- repo::manga FILTER_WHERE gains cw_include (AND, page-content-warning
  join to mangas) and cw_exclude (NONE) clauses; ListQuery + binds
  renumbered ($6/$7, LIMIT/OFFSET $8/$9).
- repo::page_analysis::warnings_for_manga: deduped, alphabetical union
  across all the manga's pages.
- domain::MangaDetail gains content_warnings; get_detail populates it.
- api::mangas list accepts cw_include/cw_exclude (reusing the shared
  parse_warnings_csv validator).

Tests: detail union (deduped/sorted) + empty case; list include/exclude
filter; unknown-warning 422. Existing manga tests still green.

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

backend/src/repo/manga.rs

@@ -35,6 +35,11 @@ pub struct ListQuery {
     pub author_ids: Vec<Uuid>,
     pub genre_ids: Vec<Uuid>,
     pub tag_ids: Vec<Uuid>,
+    /// Content warnings (canonical lowercase names) the manga must carry on
+    /// at least one page each — AND across the list.
+    pub cw_include: Vec<String>,
+    /// Content warnings the manga must NOT carry on any page.
+    pub cw_exclude: Vec<String>,
     pub limit: i64,
     pub offset: i64,
     pub sort: ListSort,
@@ -107,6 +112,21 @@ const FILTER_WHERE: &str = r#"
                  WHERE mt.manga_id = mangas.id AND mt.tag_id = req.id
              )
     )
+    AND NOT EXISTS (
+        SELECT 1 FROM unnest($6::text[]) AS req(w)
+         WHERE NOT EXISTS (
+                SELECT 1 FROM page_content_warnings pw
+                  JOIN pages p    ON p.id = pw.page_id
+                  JOIN chapters c ON c.id = p.chapter_id
+                 WHERE c.manga_id = mangas.id AND pw.warning = req.w
+             )
+    )
+    AND NOT EXISTS (
+        SELECT 1 FROM page_content_warnings pw
+          JOIN pages p    ON p.id = pw.page_id
+          JOIN chapters c ON c.id = p.chapter_id
+         WHERE c.manga_id = mangas.id AND pw.warning = ANY($7::text[])
+    )
 "#;
 
 /// Returns the page of mangas matching `query` plus the unfiltered total
@@ -130,7 +150,7 @@ pub async fn list(pool: &PgPool, query: &ListQuery) -> AppResult<(Vec<Manga>, i6
         FROM mangas
         WHERE {FILTER_WHERE}
         ORDER BY {order_by}
-        LIMIT $6 OFFSET $7
+        LIMIT $8 OFFSET $9
         "#,
         cols = manga_cols(""),
     );
@@ -141,6 +161,8 @@ pub async fn list(pool: &PgPool, query: &ListQuery) -> AppResult<(Vec<Manga>, i6
         .bind(&query.author_ids)
         .bind(&query.genre_ids)
         .bind(&query.tag_ids)
+        .bind(&query.cw_include)
+        .bind(&query.cw_exclude)
         .bind(query.limit)
         .bind(query.offset)
         .fetch_all(pool)
@@ -158,6 +180,8 @@ pub async fn list(pool: &PgPool, query: &ListQuery) -> AppResult<(Vec<Manga>, i6
         .bind(&query.author_ids)
         .bind(&query.genre_ids)
         .bind(&query.tag_ids)
+        .bind(&query.cw_include)
+        .bind(&query.cw_exclude)
         .fetch_one(pool)
         .await?;
 
@@ -266,7 +290,8 @@ pub async fn get_detail(pool: &PgPool, id: Uuid) -> AppResult<MangaDetail> {
     let authors = repo::author::list_for_manga(pool, id).await?;
     let genres = repo::genre::list_for_manga(pool, id).await?;
     let tags = repo::tag::list_for_manga(pool, id).await?;
-    Ok(MangaDetail { manga, authors, genres, tags })
+    let content_warnings = repo::page_analysis::warnings_for_manga(pool, id).await?;
+    Ok(MangaDetail { manga, authors, genres, tags, content_warnings })
 }
 
 /// Insert just the manga row. Relations (authors, genres) are written

backend/src/repo/page_analysis.rs

@@ -77,6 +77,28 @@ pub async fn enqueue_all_pages(pool: &PgPool, only_unanalyzed: bool) -> AppResul
     Ok(result.rows_affected())
 }
 
+/// Deduplicated union of content warnings across all of a manga's pages,
+/// ordered alphabetically. Powers the manga-detail content-warning banner.
+pub async fn warnings_for_manga(
+    pool: &PgPool,
+    manga_id: uuid::Uuid,
+) -> AppResult<Vec<ContentWarning>> {
+    let rows = sqlx::query_scalar::<_, ContentWarning>(
+        r#"
+        SELECT DISTINCT pw.warning
+          FROM page_content_warnings pw
+          JOIN pages p    ON p.id = pw.page_id
+          JOIN chapters c ON c.id = p.chapter_id
+         WHERE c.manga_id = $1
+         ORDER BY pw.warning
+        "#,
+    )
+    .bind(manga_id)
+    .fetch_all(pool)
+    .await?;
+    Ok(rows)
+}
+
 /// Load a page's analysis row, if it has one.
 pub async fn load(pool: &PgPool, page_id: Uuid) -> AppResult<Option<PageAnalysis>> {
     let row = sqlx::query_as::<_, PageAnalysis>(