fix(home): keep finished series off the Continue-reading shelf

A "Continue reading" shelf listing series the reader already finished (read
to the last page, nothing new) is odd. Expose the last-read chapter's
page_count on the read-progress list, and filter the shelf to drop entries
that are caught up (on the last page of the latest chapter with no new
chapters). Mid-chapter and has-new-chapters entries stay; the full history
view is unaffected. Finished detection is a pure, unit-tested helper.

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

backend/src/domain/read_progress.rs

@@ -24,6 +24,11 @@ pub struct ReadProgressSummary {
     /// `None` when the chapter was deleted after this row was written
     /// (FK ON DELETE SET NULL on `chapter_id`).
     pub chapter_number: Option<i32>,
+    /// Page count of the last-read chapter (`None` when unknown / deleted).
+    /// Lets a client distinguish a finished series (read to the last page,
+    /// nothing new) from one still in progress — e.g. to keep finished
+    /// series off a "Continue reading" shelf.
+    pub chapter_page_count: Option<i32>,
     pub page: i32,
     pub updated_at: DateTime<Utc>,
     /// How many chapters sit past the reader's last-read chapter (by

backend/src/repo/read_progress.rs

@@ -141,6 +141,7 @@ pub async fn list_for_user(
                m.cover_image_path  AS manga_cover_image_path,
                rp.chapter_id,
                c.number            AS chapter_number,
+               c.page_count        AS chapter_page_count,
                rp.page,
                rp.updated_at,
                -- Personal "new since last read": how many distinct chapter