fix(install): B10 add python3-jwt to deps so uaml-hub starts

uaml.hub.hub_server imports the PyJWT package as `jwt`, but the
"Instalace Python zavislosti" step did not install python3-jwt. Result
on a fresh install: uaml-hub.service stays in `activating` because
`python3 -m uaml.hub.hub_server` ImportErrors on `import jwt`, which
keeps the test suite from reaching T05+ (every API check sees
hub-degraded health).

Discovered while validating B6+B7+B8 fixes against pepa-pc Docker LXC
on 2026-05-01: T02 hit "service uaml-hub not active", journalctl
showed ModuleNotFoundError: No module named 'jwt' (restart counter 35+).

Fix: add `python3-jwt` to both the import-test probe and the apt-get
fallback, so the package lands before any uaml service starts.

Refs: 2026-05-01 e2e run uaml-e2e-0540 (post-B6/B7/B8 sweep).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
