feat: read & upload history (0.19.0)

Per-user reading progress and uploader attribution.

Schema (migration 0011): `read_progress` table (one row per (user,
manga); chapter_id nullable on chapter delete) and nullable
`uploaded_by` columns on mangas + chapters with partial indexes
scoped to non-null rows.

Endpoints (all `/me/*`, auth-scoped):
- PUT `/v1/me/read-progress` upserts. FK violations + cross-manga
  chapter ids both surface as 4xx (404 / 422) so the API can't be
  used to write logically invalid rows.
- GET `/v1/me/read-progress` paged newest-first list.
- GET `/v1/me/read-progress/:manga_id` enriched with chapter_number
  for the manga page's Continue CTA.
- DELETE `/v1/me/read-progress/:manga_id` idempotent.
- GET `/v1/me/uploads` interleaved manga + chapter uploads as a
  tagged union; limit-only pagination.

Existing manga + chapter upload handlers stamp `uploaded_by`.

Frontend:
- Reader emits progress on mount + page change (debounce) and via
  IntersectionObserver in continuous mode. High-water mark is seeded
  from the persisted server value so re-opening a chapter doesn't
  regress to page 1. Tab close survives via `sendBeacon` (fallback
  `keepalive` fetch); SPA navigation flushes via regular fetch.
- Manga detail page shows "Continue reading Chapter N — page M"
  above the chapters list, working even for mangas with >50
  chapters.
- New `/profile/history` tab with reading history (clear-per-row,
  inline error on failure) and uploads (mangas + chapters mixed
  chronologically with type-aware rendering).

171 backend tests (incl. 16 history tests covering ownership, FK
race, cross-link guard, chapter SET NULL behaviour) and 97 frontend
tests + svelte-check clean.

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

frontend/src/lib/api/uploads.ts

@@ -0,0 +1,42 @@
+import { ApiError, request, type Manga, type Page } from './client';
+import type { Chapter } from './chapters';
+
+/**
+ * Tagged union returned by `GET /v1/me/uploads`. The discriminant lives
+ * on the `kind` field; pattern-match on it before accessing the rest.
+ */
+export type UploadEntry =
+    | { kind: 'manga'; manga: Manga; created_at: string }
+    | {
+          kind: 'chapter';
+          manga_id: string;
+          manga_title: string;
+          manga_cover_image_path: string | null;
+          chapter: Chapter;
+          created_at: string;
+      };
+
+export type UploadsPage = {
+    items: UploadEntry[];
+    page: Page;
+};
+
+export async function listMyUploads(
+    opts: { limit?: number } = {}
+): Promise<UploadsPage> {
+    const params = new URLSearchParams();
+    if (opts.limit != null) params.set('limit', String(opts.limit));
+    const qs = params.toString();
+    return request<UploadsPage>(`/v1/me/uploads${qs ? `?${qs}` : ''}`);
+}
+
+export async function listMyUploadsOrEmpty(): Promise<UploadsPage> {
+    try {
+        return await listMyUploads();
+    } catch (e) {
+        if (e instanceof ApiError && e.status === 401) {
+            return { items: [], page: { limit: 50, offset: 0, total: null } };
+        }
+        throw e;
+    }
+}