**Add continuous reading mode and enhance accessibility in TheComicReader**

- Introduced a continuous reading mode ("scroll"), allowing users to read without pagination.
- Implemented a toggle in the UI to switch between "paged" and "continuous" modes, with preferences saved in `localStorage`.
- Enhanced keyboard navigation by throttling repeated actions and ignoring irrelevant keypresses during form interactions.
- Integrated `IntersectionObserver` to handle lazy-loading of images and dynamically extending rendered content in continuous mode.
- Updated tests to validate both reading modes, ensuring proper state management and observer handling.
- Adjusted animations and transitions for smoother visual feedback in both modes, respecting users' motion-reduction preferences.

cbreader/crontab

@@ -1 +1,3 @@
-*/15 * * * * root /opt/venv/bin/python /src/manage.py scan_comics --settings=cbreader.settings.base
+# Cron captures job output for e-mail, which is discarded without an MTA, so write to
+# the cron daemon's own stderr instead - that is what `docker logs` shows.
+*/15 * * * * root /opt/venv/bin/python /src/manage.py scan_comics --settings=cbreader.settings.base >> /proc/1/fd/2 2>&1