feat(home): add a Continue-reading shelf with new-chapter badges

Surface a horizontal "Continue reading" shelf at the top of the homepage,
fed by the user's read-progress history. Each card jumps back to the exact
page they left off (deep-linking `?page=N` past the first) and flags how
many chapters have landed since — the personal new_chapters_count from the
read-progress list. The shelf is fetched after the catalogue load so the
public browse path stays unauthenticated; guests get an empty list (401
swallowed) and the shelf stays hidden.

Add new_chapters_count to the frontend ReadProgressSummary type to match
the backend. Component unit tests cover href/deep-link, badge visibility,
and the no-chapter fallback; e2e covers signed-in (shelf + badge) and
anonymous (hidden).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.95.0",
+  "version": "0.96.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "mangalord-frontend",
-      "version": "0.95.0",
+      "version": "0.96.0",
       "devDependencies": {
         "@lucide/svelte": "^1.16.0",
         "@playwright/test": "^1.48.0",