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.

web/src/series.ts

@@ -1,16 +1,23 @@
 import { Alpine } from "./alpine";
 import { initLibrarySwitcher } from "./library-switcher";
 
-// Rendering ownership (AGENTS.md): the series grid and its paginator are
-// rendered by templates/series.templ. This page intentionally has NO
-// TypeScript renderer — the old one here duplicated the templ markup via
-// innerHTML and re-fetched at hardcoded page 1, stomping SSR pagination
-// whenever the header's library restore fired. A library switch is a plain
-// SSR navigation so the URL stays the single source of truth for
-// library_id and page state.
+// Rendering ownership (AGENTS.md): the series grid, its paginator and
+// its sort/filter toolbar are rendered by templates/series.templ. This
+// page intentionally has NO TypeScript renderer — the old one here
+// duplicated the templ markup via innerHTML and re-fetched at hardcoded
+// page 1, stomping SSR pagination whenever the header's library restore
+// fired. A library switch is a plain SSR navigation so the URL stays
+// the single source of truth for library_id, page AND sort/filter state
+// (the switch carries the current q/author/status/sort params along).
 function navigateToSeries(libraryId: string): void {
-  const param = libraryId ? `library_id=${encodeURIComponent(libraryId)}&` : "";
-  window.location.href = `/series?${param}page=1`;
+  const params = new URLSearchParams(window.location.search);
+  if (libraryId) {
+    params.set("library_id", libraryId);
+  } else {
+    params.delete("library_id");
+  }
+  params.set("page", "1");
+  window.location.href = `/series?${params.toString()}`;
 }
 
 Alpine.data("seriesPage", () => ({