feat(series): multi-field search, sort-direction toggle, apply placement

Toolbar feedback round: the series search box now matches whatever the
main search matches for a group — series NAME, any book's AUTHOR, and
any book's TITLE inside the series (WHERE EXISTS per group-row, so
counts stay true); the separate author input is gone from the toolbar
(the author= param stays live for the JSON API and deep links). The
sort control becomes a base-key select (Date added/Name/Author/Books/
Progress/Last read) plus a chevron direction toggle that flips and
resubmits; sort/dir compose through ResolveSeriesSort (full registry
keys keep working for back-compat, unknown base keys fall to recent).
The search/apply button moved next to the search box as requested, and
default URLs stay clean (sort/dir only emitted once the user chooses).

templates/series.templ

@@ -8,23 +8,19 @@ import (
 
 // seriesSortOptions is the <select> mirror of the SQL CASE cascade in
 // GetDistinctSeries and the registry in services.ResolveSeriesSort —
-// every value here must have a matching SQL arm and registry entry.
+// every value here must have a matching base sort in
+// services.seriesBaseSorts (the direction toggle composes the full
+// registry key).
 var seriesSortOptions = []struct {
 	Value string
 	Label string
 }{
-	{"recent", "Recently added"},
-	{"recent_asc", "Oldest added"},
-	{"name_asc", "Name (A–Z)"},
-	{"name_desc", "Name (Z–A)"},
-	{"author_asc", "Author (A–Z)"},
-	{"author_desc", "Author (Z–A)"},
-	{"books_desc", "Most books"},
-	{"books_asc", "Fewest books"},
-	{"progress_desc", "Most complete"},
-	{"progress_asc", "Least complete"},
-	{"last_read_desc", "Recently read"},
-	{"last_read_asc", "Least recently read"},
+	{"recent", "Date added"},
+	{"name", "Name"},
+	{"author", "Author"},
+	{"books", "Books"},
+	{"progress", "Progress"},
+	{"last_read", "Last read"},
 }
 
 // seriesStatusOptions is the progress-filter <select> (mirror of the
@@ -49,12 +45,12 @@ func seriesPageURL(state SeriesPageState, libraryID string, page int) string {
 	if state.Sort != "" {
 		vals.Set("sort", state.Sort)
 	}
+	if state.Dir != "" {
+		vals.Set("dir", state.Dir)
+	}
 	if state.Query != "" {
 		vals.Set("q", state.Query)
 	}
-	if state.Author != "" {
-		vals.Set("author", state.Author)
-	}
 	if state.Status != "" {
 		vals.Set("status", state.Status)
 	}
@@ -66,7 +62,7 @@ func seriesPageURL(state SeriesPageState, libraryID string, page int) string {
 // page's defaults — used to swap the empty state for a
 // "no matches" + clear-filters variant.
 func hasActiveSeriesFilters(state SeriesPageState) bool {
-	return state.Query != "" || state.Author != "" || state.Status != "" || (state.Sort != "" && state.Sort != "recent")
+	return state.Query != "" || state.Status != "" || (state.Sort != "" && state.Sort != "recent")
 }
 
 templ Series(user User, seriesList []SeriesCardData, libData []LibraryData, currentLibraryID string, totalPages int, currentPage int, state SeriesPageState, errorMessage string) {
@@ -108,19 +104,15 @@ templ Series(user User, seriesList []SeriesCardData, libData []LibraryData, curr
 								type="text"
 								name="q"
 								value={ state.Query }
-								placeholder="Search series…"
+								placeholder="Search series, authors, titles…"
 								class="input w-full pl-9"
-								aria-label="Search series by name"
+								aria-label="Search series by name, author, or title"
 							/>
 						</div>
-						<input
-							type="text"
-							name="author"
-							value={ state.Author }
-							placeholder="Author"
-							class="input w-40"
-							aria-label="Filter series by author"
-						/>
+						<button type="submit" class="btn btn-secondary" aria-label="Search">
+							@Icon("search", "h-4 w-4")
+							<span>Search</span>
+						</button>
 						<select
 							name="status"
 							class="input w-auto cursor-pointer"
@@ -134,16 +126,26 @@ templ Series(user User, seriesList []SeriesCardData, libData []LibraryData, curr
 						<select
 							name="sort"
 							class="input w-auto cursor-pointer"
-							aria-label="Sort series"
+							aria-label="Sort series by"
 							@change="$el.form.requestSubmit()"
 						>
 							for _, opt := range seriesSortOptions {
 								<option value={ opt.Value } selected?={ (state.Sort == "" && opt.Value == "recent") || state.Sort == opt.Value }>{ opt.Label }</option>
 							}
 						</select>
-						<button type="submit" class="btn btn-secondary" aria-label="Apply filters">
-							@Icon("filter", "h-4 w-4")
-							<span>Apply</span>
+						<input type="hidden" name="dir" value={ state.Dir } x-ref="sortDir"/>
+						<button
+							type="button"
+							class="btn btn-secondary px-3"
+							aria-label="Toggle sort direction"
+							title="Toggle sort direction"
+							@click="flipSortDir()"
+						>
+							if state.Dir == "asc" {
+								@Icon("chevron-up", "h-4 w-4")
+							} else {
+								@Icon("chevron-down", "h-4 w-4")
+							}
 						</button>
 					</form>
 					if len(seriesList) == 0 {