fix(ui): install prod deps in Docker runtime; add reindex endpoint for chapters_idx

- ui/Dockerfile: copy package-lock.json and run npm ci --omit=dev in the
  runtime stage so marked (and other runtime deps) are available to
  adapter-node at startup — fixes ERR_MODULE_NOT_FOUND for 'marked'
- storage: add ReindexChapters to Store interface and HybridStore — walks
  MinIO objects for a slug, reads chapter titles, upserts chapters_idx
- server: add POST /api/reindex/{slug} to rebuild chapters_idx from MinIO

scraper/internal/storage/hybrid.go

@@ -140,6 +140,73 @@ func (h *HybridStore) CountChapters(ctx context.Context, slug string) int {
 	return h.pb.CountChapterIdx(ctx, slug)
 }
 
+// ReindexChapters walks all MinIO objects for slug, reads the title from the
+// first line of each chapter markdown, and upserts them into chapters_idx.
+// This repairs the PocketBase index when it falls out of sync with MinIO.
+// Returns the number of chapters indexed and any non-fatal errors encountered.
+func (h *HybridStore) ReindexChapters(ctx context.Context, slug string) (int, error) {
+	keys, err := h.minio.ListChapterKeys(ctx, slug)
+	if err != nil {
+		return 0, fmt.Errorf("reindex: list chapter keys: %w", err)
+	}
+
+	count := 0
+	var errs []string
+	for _, key := range keys {
+		// Parse chapter number from key: {slug}/vol-N/lo-hi/chapter-N.md
+		n := chapterNumberFromKey(key)
+		if n <= 0 {
+			h.log.Warn("ReindexChapters: could not parse chapter number from key", "key", key)
+			continue
+		}
+
+		raw, readErr := h.minio.GetChapter(ctx, slug, 0, n)
+		if readErr != nil {
+			errs = append(errs, fmt.Sprintf("ch%d: %v", n, readErr))
+			continue
+		}
+
+		// Extract title from first line ("# Title text") or fall back to empty.
+		rawTitle := ""
+		if line, _, found := strings.Cut(raw, "\n"); found || raw != "" {
+			rawTitle = strings.TrimPrefix(strings.TrimSpace(line), "# ")
+		}
+		title, dateLabel := splitChapterTitle(rawTitle)
+
+		if upsertErr := h.pb.UpsertChapterIdx(ctx, slug, n, title, dateLabel); upsertErr != nil {
+			errs = append(errs, fmt.Sprintf("ch%d upsert: %v", n, upsertErr))
+			continue
+		}
+		count++
+	}
+
+	if len(errs) > 0 {
+		return count, fmt.Errorf("reindex: %d error(s): %s", len(errs), strings.Join(errs, "; "))
+	}
+	return count, nil
+}
+
+// chapterNumberFromKey parses the chapter number from a MinIO object key of the
+// form "{slug}/vol-N/lo-hi/chapter-N.md".
+func chapterNumberFromKey(key string) int {
+	// Grab the filename portion after the last '/'.
+	_, file, _ := strings.Cut(key, "/")
+	parts := strings.Split(key, "/")
+	if len(parts) == 0 {
+		return 0
+	}
+	filename := parts[len(parts)-1]
+	// filename is "chapter-N.md"
+	filename = strings.TrimSuffix(filename, ".md")
+	filename = strings.TrimPrefix(filename, "chapter-")
+	n, err := strconv.Atoi(filename)
+	if err != nil || n <= 0 {
+		return 0
+	}
+	_ = file
+	return n
+}
+
 // ─── Ranking ─────────────────────────────────────────────────────────────────
 
 func (h *HybridStore) WriteRankingItem(ctx context.Context, item RankingItem) error {

scraper/internal/storage/store.go

@@ -91,6 +91,9 @@ type Store interface {
 	ListChapters(ctx context.Context, slug string) ([]ChapterInfo, error)
 	// CountChapters returns the number of stored chapters for slug.
 	CountChapters(ctx context.Context, slug string) int
+	// ReindexChapters rebuilds chapters_idx from MinIO objects for slug.
+	// Returns the number of chapters indexed.
+	ReindexChapters(ctx context.Context, slug string) (int, error)
 
 	// ── Ranking ────────────────────────────────────────────────────────────