fix(scanner): reliable cookie discovery, auto-categorisation, and scan scheduling UI (#7)

Scanner fixes:
- Remove conflicting ``path`` from consent pre-seed cookie (Playwright
  rejects cookies with both ``url`` and ``path``).
- Switch to ``networkidle`` + 5s + 2s delayed second-pass for reliable
  cookie capture.
- Check sitemap Content-Type to skip SPA HTML fallbacks.
- Propagate ``auto_category`` from scan results to the cookies table
  during sync (was silently dropped).
- Add ``_gcl_ls`` to the Open Cookie Database CSV.
- Classify ``_consentos_*`` cookies as necessary directly in the
  classification engine.
- Add ``seed_known_cookies`` to the bootstrap init container command.

Admin UI:
- Add scan schedule control to the Scans tab — preset options
  (disabled/daily/weekly/fortnightly/monthly) plus custom cron input.
  Saves ``scan_schedule_cron`` on the site config.

docker-compose.prod.yml

@@ -27,7 +27,7 @@ services:
     command:
       - "sh"
       - "-c"
-      - "python -m alembic upgrade head && python -m src.cli.bootstrap_admin"
+      - "python -m alembic upgrade head && python -m src.cli.bootstrap_admin && python -m src.cli.seed_known_cookies"
     restart: "no"
     depends_on:
       postgres: