feat(series): sort and filter the series page

The /series page rendered its grid in one fixed order (newest first)
with no way to find a series beyond eyeballing cards. The page now has
a toolbar — series-name search, author filter, viewer-progress filter
and a 12-key sort select — wired as a plain GET form (the page's
existing model: the URL is the single source of truth, and the library
switcher now carries q/author/status/sort along on switch).

Extensibility is deliberate (user request): sorts live in a registry
(services.ResolveSeriesSort) mirrored by a CASE cascade in
GetDistinctSeries and a <select> in series.templ — a new sort is one
entry in each. The sort value is a BOUND PARAM compared inside the
cascade, never interpolated; unknown keys resolve to the default.
Filters: series-name matches in WHERE (the group key, so counts stay
true); author (BOOL_OR any-book match) and status (finished/reading/
unstarted vs the viewer's progress, same 0.999 threshold as the
filter_query status arms) in HAVING so COUNT(*) keeps reporting the
whole series. GetDistinctSeriesCount shares the JOIN + HAVING so
pagination totals match. The reading_progress join can't multiply rows
(the table is UNIQUE per media_item+user).

Cards gain the viewer's finished-count ("X of N read" + progress bar),
and the empty state distinguishes "no series at all" from "no matches —
clear filters". The JSON /api/series endpoint takes the same params and
gains read_count/last_read_at additively.

Integration test pins every sort key against a three-series fixture
with distinct created/author/count/progress answers, the filter matrix,
composition, unknown-sort fallback, card read-counts and the JSON
contract — all as the fresh regular user so the live reader's data is
untouched.

internal/handlers/series.go

@@ -64,7 +64,19 @@ func (h *SeriesHandler) GetSeries(c *echo.Context) error {
 		return c.JSON(http.StatusForbidden, map[string]string{"error": "library not accessible"})
 	}
 
-	seriesList, total, err := h.seriesService.GetSeriesPage(c.Request().Context(), libUUID, visibleIDs, limit, offset)
+	// Sort/filter params (same contract as the SSR /series page):
+	// unknown values resolve to defaults inside the service.
+	opts := services.SeriesPageOptions{
+		Sort:   c.QueryParam("sort"),
+		Query:  c.QueryParam("q"),
+		Author: c.QueryParam("author"),
+		Status: c.QueryParam("status"),
+	}
+	if u, ok := c.Get("user").(database.Users); ok {
+		opts.ViewerUserID = u.ID
+	}
+
+	seriesList, total, err := h.seriesService.GetSeriesPage(c.Request().Context(), libUUID, visibleIDs, limit, offset, opts)
 	if err != nil {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to load series"})
 	}
@@ -76,6 +88,8 @@ func (h *SeriesHandler) GetSeries(c *echo.Context) error {
 		TotalInSeries int      `json:"total_in_series"`
 		CoverPaths    []string `json:"cover_paths"`
 		LastEntryAt   string   `json:"last_entry_at"`
+		ReadCount     int64    `json:"read_count"`
+		LastReadAt    string   `json:"last_read_at"`
 	}
 
 	response := make([]SeriesResponse, 0, len(seriesList))
@@ -87,6 +101,8 @@ func (h *SeriesHandler) GetSeries(c *echo.Context) error {
 			TotalInSeries: s.TotalInSeries,
 			CoverPaths:    s.CoverPaths,
 			LastEntryAt:   s.LastEntryAt,
+			ReadCount:     s.ReadCount,
+			LastReadAt:    s.LastReadAt,
 		})
 	}
 
@@ -150,7 +166,7 @@ func (h *SeriesHandler) GetSeriesBooks(c *echo.Context) error {
 	})
 }
 
-func GetSeriesCardsData(ctx context.Context, db *database.Queries, libraryID pgtype.UUID, visibleLibraryIDs []pgtype.UUID, limit, offset int) ([]services.SeriesInfo, int, error) {
+func GetSeriesCardsData(ctx context.Context, db *database.Queries, libraryID pgtype.UUID, visibleLibraryIDs []pgtype.UUID, limit, offset int, opts services.SeriesPageOptions) ([]services.SeriesInfo, int, error) {
 	svc := services.NewSeriesService(db)
-	return svc.GetSeriesPage(ctx, libraryID, visibleLibraryIDs, limit, offset)
+	return svc.GetSeriesPage(ctx, libraryID, visibleLibraryIDs, limit, offset, opts)
 }