fix: extend CORS origins to comix and kagane, preserve progress on unparseable chapters

- .env.example, DEPLOY.md, docker-compose.yml: add comix.to/kagane.to to
  ALLOWED_ORIGINS so the userscript isn't CORS-blocked on either new site
- .env.example: comment out BROWSER_WS_URL's DNS-name default, which
  overrides the working compose default and 500s Chrome's DevTools handler
- userscript: updateToCurrentChapter() now falls back to the stored
  chapter/label when chapterNum is unparseable, instead of wiping progress
  (kagane's og:title lacks a number when a chapter has no episode suffix)
- README.md: document comix/kagane in the config table, adapter reference,
  and key examples

DEPLOY.md

@@ -36,7 +36,7 @@ Edit `.env`:
 API_TOKEN=<paste output of: openssl rand -hex 32>
 
 # CORS allowlist — leave as-is unless a site changes hostname.
-ALLOWED_ORIGINS=https://asuracomic.net,https://asurascans.com,https://demonicscans.org
+ALLOWED_ORIGINS=https://asuracomic.net,https://asurascans.com,https://demonicscans.org,https://comix.to,https://kagane.to
 
 # Required for the Traefik override. Both have no fallback — compose refuses
 # to start without them. MANGA_WEB_HOST is required even if you never set