Build injects __WEATHER_COMMIT__ (VITE_COMMIT_HASH from CI's github.sha on
branch builds, git rev-parse HEAD locally) and main.js logs
console.info({ commit_hash }) so a deploy can be verified to match the
commit that produced it.
Deploys dist/index.html to the WebDAV mirror via basic-auth curl PUT from
WEBDAV_USER/WEBDAV_PASS repo secrets, then verifies the deployed bytes
match the local build. Hard-fails if the secrets are missing so a silent
non-deploy can never look like a success.
