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

docker-compose.yml

@@ -15,7 +15,7 @@ services:
     environment:
       # API_TOKEN is required — compose refuses to start without it.
       API_TOKEN: ${API_TOKEN:?set API_TOKEN in .env}
-      ALLOWED_ORIGINS: ${ALLOWED_ORIGINS:-https://asuracomic.net,https://asurascans.com,https://demonicscans.org}
+      ALLOWED_ORIGINS: ${ALLOWED_ORIGINS:-https://asuracomic.net,https://asurascans.com,https://demonicscans.org,https://comix.to,https://kagane.to}
       DB_PATH: /data/bookmarks.db
       PORT: "8080"
       # Gates the browser UI. Unset means the web routes are not served at all.