feat(mangas): per-field sort options + direction toggle on the catalog (0.88.0)

Sort the manga catalog by created / updated / title / author with an
independent asc/desc direction control. An omitted `order` defaults per field
(dates newest-first, text A→Z), matching the UI, so a bare `?sort=<field>`
means the same thing in the browser and over the API; `sort=recent` remains a
back-compat alias for `created`.

- Backend: SortField/SortOrder parsed with validation (structured 422 on bad
  input), per-field default_order, NULLS LAST only on the nullable author key,
  and migration 0033 indexing mangas(updated_at DESC, id) to back the default
  sort and its id tie-break.
- Frontend: catalog sort field + direction (SegmentedControl) on desktop and a
  mobile bottom sheet; pure helpers in $lib/mangaSort; keyboard-accessible
  direction control; visible Direction labels and a sheet "Done" button.
- Tests: backend integration coverage (defaults, alias, invalid input,
  ascending-id tie-break), frontend unit + e2e.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/routes/+page.svelte

@@ -7,13 +7,25 @@
         listMangas,
         type MangaCard as MangaCardData,
         type MangaSort,
+        type SortOrder,
         type MangaStatus
     } from '$lib/api/mangas';
     import { listGenres, type Genre } from '$lib/api/genres';
     import { listTags, type Tag } from '$lib/api/tags';
+    import {
+        DEFAULT_SORT,
+        SORT_FIELD_LABELS,
+        defaultOrderFor,
+        dirOptions as dirOptionsFor,
+        coerceSort,
+        coerceOrder,
+        sortLabel as composeSortLabel,
+        sortUrlParams
+    } from '$lib/mangaSort';
     import Chip from '$lib/components/Chip.svelte';
     import MangaCard from '$lib/components/MangaCard.svelte';
     import Pager from '$lib/components/Pager.svelte';
+    import SegmentedControl from '$lib/components/SegmentedControl.svelte';
     import Sheet from '$lib/components/Sheet.svelte';
     import Search from '@lucide/svelte/icons/search';
     import SlidersHorizontal from '@lucide/svelte/icons/sliders-horizontal';
@@ -25,7 +37,8 @@
 
     let mangas: MangaCardData[] = $state([]);
     let search = $state('');
-    let sort = $state<MangaSort>('recent');
+    let sort = $state<MangaSort>(DEFAULT_SORT);
+    let order = $state<SortOrder>(defaultOrderFor(DEFAULT_SORT));
     let statusFilter = $state<'' | MangaStatus>('');
     let selectedGenres = $state<Genre[]>([]);
     let selectedTags = $state<Tag[]>([]);
@@ -55,7 +68,12 @@
         (statusFilter ? 1 : 0) + selectedGenres.length + selectedTags.length
     );
 
-    const sortLabel = $derived(sort === 'title' ? 'Title (A→Z)' : 'Recent');
+    // Field/direction labelling and defaults live in $lib/mangaSort (unit
+    // tested there). Date fields read newest-first; text fields A→Z. The
+    // direction stays freely togglable — defaultOrderFor only picks the
+    // direction applied when the field changes.
+    const dirOptions = $derived(dirOptionsFor(sort));
+    const sortLabel = $derived(composeSortLabel(sort, order));
 
     const totalPages = $derived(
         total != null && total > 0 ? Math.ceil(total / PAGE_SIZE) : 1
@@ -76,6 +94,7 @@
                 genreIds: selectedGenres.map((g) => g.id),
                 tagIds: selectedTags.map((t) => t.id),
                 sort,
+                order,
                 limit: PAGE_SIZE,
                 offset: (currentPage - 1) * PAGE_SIZE
             });
@@ -92,7 +111,11 @@
         if (!browser) return;
         const params = new URLSearchParams();
         if (search.trim()) params.set('q', search.trim());
-        if (sort !== 'recent') params.set('sort', sort);
+        // Defaults are omitted to keep the URL clean; the backend resolves an
+        // absent `sort`/`order` the same way, so the omission is unambiguous.
+        const sp = sortUrlParams(sort, order);
+        if (sp.sort) params.set('sort', sp.sort);
+        if (sp.order) params.set('order', sp.order);
         if (statusFilter) params.set('status', statusFilter);
         if (selectedGenres.length)
             params.set('genres', selectedGenres.map((g) => g.id).join(','));
@@ -126,8 +149,10 @@
         // Genre objects so the chip rows render real labels.
         const url = new URL($page.url);
         search = url.searchParams.get('q') ?? '';
-        const s = url.searchParams.get('sort');
-        if (s === 'title' || s === 'recent') sort = s;
+        sort = coerceSort(url.searchParams.get('sort'));
+        // Fall back to the field's natural default when `order` is absent or
+        // invalid, mirroring how syncUrl omits the default.
+        order = coerceOrder(url.searchParams.get('order'), sort);
         const st = url.searchParams.get('status');
         statusFilter = st === 'ongoing' || st === 'completed' ? st : '';
         const genreIds = (url.searchParams.get('genres') ?? '')
@@ -166,6 +191,15 @@
     }
 
     function onSortChange() {
+        // Changing the field snaps the direction back to that field's natural
+        // default (dates → Newest, text → A→Z); the user can flip afterwards.
+        order = defaultOrderFor(sort);
+        resetAndReload();
+    }
+
+    function pickOrder(next: SortOrder) {
+        if (next === order) return;
+        order = next;
         resetAndReload();
     }
 
@@ -249,12 +283,12 @@
     }
 
     function pickSort(next: MangaSort) {
-        if (next === sort) {
-            sortSheetOpen = false;
-            return;
-        }
+        if (next === sort) return;
         sort = next;
-        sortSheetOpen = false;
+        // Match desktop: snap to the field's natural direction. The sheet
+        // stays open so the user can also adjust the direction before
+        // dismissing it.
+        order = defaultOrderFor(sort);
         resetAndReload();
     }
 
@@ -504,10 +538,22 @@
         <label class="sort">
             <span>Sort</span>
             <select bind:value={sort} onchange={onSortChange} data-testid="sort-select">
-                <option value="recent">Recent</option>
-                <option value="title">Title (A→Z)</option>
+                <option value="updated">Last updated</option>
+                <option value="created">Date added</option>
+                <option value="title">Title</option>
+                <option value="author">Author</option>
             </select>
         </label>
+        <div class="sort">
+            <span>Direction</span>
+            <SegmentedControl
+                options={dirOptions}
+                value={order}
+                onchange={pickOrder}
+                ariaLabel="Sort direction"
+                testid="sort-order"
+            />
+        </div>
     </div>
 </form>
 
@@ -526,30 +572,44 @@
     onClose={() => (sortSheetOpen = false)}
     testid="sort-sheet"
 >
-    <div class="sort-options">
-        <label>
-            <input
-                type="radio"
-                name="sort-mobile"
-                value="recent"
-                aria-label="Recent"
-                checked={sort === 'recent'}
-                onchange={() => pickSort('recent')}
-            />
-            <span>Recent</span>
-        </label>
-        <label>
-            <input
-                type="radio"
-                name="sort-mobile"
-                value="title"
-                aria-label="Title (A→Z)"
-                checked={sort === 'title'}
-                onchange={() => pickSort('title')}
-            />
-            <span>Title (A→Z)</span>
-        </label>
+    <p id="sort-field-heading" class="sort-section-label">Sort by</p>
+    <div class="sort-options" role="radiogroup" aria-labelledby="sort-field-heading">
+        {#each Object.entries(SORT_FIELD_LABELS) as [value, label] (value)}
+            <label>
+                <input
+                    type="radio"
+                    name="sort-mobile"
+                    {value}
+                    aria-label={label}
+                    checked={sort === value}
+                    onchange={() => pickSort(value as MangaSort)}
+                />
+                <!-- aria-label duplicates the visible span text on purpose so
+                     the e2e getByRole('radio', { name }) lookup is stable. -->
+                <span>{label}</span>
+            </label>
+        {/each}
     </div>
+    <div class="sort-direction">
+        <p class="sort-section-label">Direction</p>
+        <SegmentedControl
+            options={dirOptions}
+            value={order}
+            onchange={pickOrder}
+            ariaLabel="Sort direction"
+            testid="sort-order-mobile"
+        />
+    </div>
+    {#snippet footer()}
+        <button
+            type="button"
+            class="primary"
+            onclick={() => (sortSheetOpen = false)}
+            data-testid="sort-done"
+        >
+            Done
+        </button>
+    {/snippet}
 </Sheet>
 
 {#if loading}
@@ -836,6 +896,32 @@
         cursor: pointer;
     }
 
+    .sort-direction {
+        margin-top: var(--space-3);
+        padding-top: var(--space-3);
+        border-top: 1px solid var(--border);
+    }
+
+    /* Section headings inside the mobile sort sheet ("Sort by" / "Direction")
+       so each group is visibly labelled, mirroring the desktop inline labels. */
+    .sort-section-label {
+        margin: 0 0 var(--space-2);
+        font-size: var(--font-sm);
+        font-weight: var(--weight-medium);
+        color: var(--text-muted);
+    }
+
+    .primary {
+        border: 1px solid var(--primary);
+        background: var(--primary);
+        color: var(--primary-contrast);
+    }
+
+    .primary:hover {
+        background: var(--primary-hover);
+        border-color: var(--primary-hover);
+    }
+
     .icon-btn {
         display: inline-flex;
         align-items: center;