TS Pro Backup v1.2.1 — fix HTTPS login regression

TS Pro Backup v1.2.1

Hotfix. Fixes a regression that broke console sign-in over HTTPS.

The bug

On a TLS deployment (the recommended production setup), logging in — and every
other console form — failed with:

400 Bad Request
The referrer header is missing.

The Referrer-Policy: no-referrer header added in 1.1.0 told browsers never to
send the Referer header, but Flask-WTF's CSRF protection performs a strict
referrer check over HTTPS and rejects a form POST whose Referer is missing.

The fix

The policy is now Referrer-Policy: same-origin: the Referer is sent on
same-origin requests (so CSRF passes) and still withheld from external sites.

Who should upgrade

Anyone running 1.1.0 or 1.2.0 behind HTTPS — sign-in is broken on those
versions. Upgrade with:

docker compose pull && docker compose up -d

No data or configuration changes.

License

AGPL-3.0-or-later.