feat: manga metadata with status, authors, genres, tags, and search filters (0.15.0)

Adds first-class manga metadata across the stack:

- **Status** (ongoing / completed), **alternative titles**, normalized
  **multi-author** support, **curated genres** (13 seeded), and
  **free-form user tags** (case-insensitive, globally shared). Each is
  modelled as its own table joined to mangas; `mangas.author` is
  backfilled into `authors` + `manga_authors` and dropped.
- New endpoints: `PATCH /v1/mangas/:id` (three-state `description`),
  `POST/DELETE /v1/mangas/:id/tags[/:tag_id]`, `GET /v1/genres`,
  `GET /v1/tags?search=`.
- `GET /v1/mangas` now returns `MangaCard` (with authors + genres
  batched in) and supports `?status=`, `?author_id=`, `?genre_id=`,
  `?tag_id=` filters — AND across facets, with empty-array no-op
  semantics for the unnest primitive.
- `GET /v1/mangas/:id` returns the enriched `MangaDetail` with tags.
- Frontend: reusable `Chip` component; manga detail page renders
  authors as chips linking to `/authors/:id` (Phase 2), a status
  badge, alt titles, genres, and tags with inline add/remove (only
  the attacher sees remove); upload form supports multi-author /
  multi-genre / alt titles / status; search page gets a collapsible
  URL-synced filter panel with keyboard-navigable tag autocomplete.
- 126 backend tests (incl. AND-across-facets primitive, case-insens
  author/tag de-dup, transactional create rollback, PATCH semantics
  for missing / null / set on description); 72 frontend tests +
  svelte-check clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/Chip.svelte

@@ -0,0 +1,118 @@
+<script lang="ts">
+    import X from '@lucide/svelte/icons/x';
+
+    type Variant = 'neutral' | 'primary' | 'soft';
+
+    let {
+        label,
+        href,
+        variant = 'neutral',
+        onRemove,
+        removeLabel = 'Remove',
+        testid
+    }: {
+        label: string;
+        href?: string;
+        variant?: Variant;
+        onRemove?: () => void;
+        removeLabel?: string;
+        testid?: string;
+    } = $props();
+</script>
+
+{#if href}
+    <a class="chip {variant}" {href} data-testid={testid}>
+        <span class="chip-label">{label}</span>
+        {#if onRemove}
+            <button
+                type="button"
+                class="chip-remove"
+                aria-label={removeLabel}
+                title={removeLabel}
+                onclick={(e) => {
+                    e.preventDefault();
+                    onRemove?.();
+                }}
+            >
+                <X size={12} aria-hidden="true" />
+            </button>
+        {/if}
+    </a>
+{:else}
+    <span class="chip {variant}" data-testid={testid}>
+        <span class="chip-label">{label}</span>
+        {#if onRemove}
+            <button
+                type="button"
+                class="chip-remove"
+                aria-label={removeLabel}
+                title={removeLabel}
+                onclick={() => onRemove?.()}
+            >
+                <X size={12} aria-hidden="true" />
+            </button>
+        {/if}
+    </span>
+{/if}
+
+<style>
+    .chip {
+        display: inline-flex;
+        align-items: center;
+        gap: var(--space-1);
+        padding: 2px var(--space-2);
+        border-radius: var(--radius-pill);
+        font-size: var(--font-xs);
+        font-weight: var(--weight-medium);
+        line-height: var(--leading-tight);
+        background: var(--surface-elevated);
+        border: 1px solid var(--border);
+        color: var(--text);
+        text-decoration: none;
+        white-space: nowrap;
+    }
+
+    a.chip:hover {
+        background: var(--primary-soft-bg);
+        border-color: var(--primary);
+        color: var(--text);
+        text-decoration: none;
+    }
+
+    .chip.primary {
+        background: var(--primary-soft-bg);
+        border-color: var(--primary);
+    }
+
+    .chip.soft {
+        background: transparent;
+        border-color: var(--border-strong);
+        color: var(--text-muted);
+    }
+
+    .chip-label {
+        overflow: hidden;
+        text-overflow: ellipsis;
+    }
+
+    .chip-remove {
+        display: inline-flex;
+        align-items: center;
+        justify-content: center;
+        width: 16px;
+        height: 16px;
+        padding: 0;
+        background: transparent;
+        border: 0;
+        color: inherit;
+        opacity: 0.6;
+        cursor: pointer;
+        border-radius: var(--radius-pill);
+    }
+
+    .chip-remove:hover {
+        opacity: 1;
+        background: var(--danger-soft-bg);
+        color: var(--danger);
+    }
+</style>