➕(backend) add a JOSE dependency

We will add a JWKs endpoint to the application
and manipulate signed/encrypted Json Web Token (JWT).

Project lacks tooling for JSON Object Signing and Encryption (JOSE)
manipulations. After a quick benchmark, 'joserfc' has been chosen
as the dependency to add.

joserfc is a Python library that provides a comprehensive
implementation of several essential JOSE standards.

Please find the benchmark:

- Cryptography: Although using only cryptography is feasible, its
  interface/API is not as user-friendly.

- pyjwt: While pyjwt is popular, it lacks support for JWK and JWE objects,
  which are essential for the requirements.

- python-jose: The latest release of python-jose was in 2021, and the
  project seems less active compared to other alternatives.

- Authlib: Authlib is the second most popular library after pyjwt and seems
  modern with an active community. However, the parts relevant to the use case
  were extracted into a relatively new package named joserfc.

- joserfc: Although joserfc has fewer stars compared to Authlib, it was
  extracted from Authlib, which has more than 4k stars, indicating a solid
  foundation.

While the low star count of joserfc might raise concerns about its stability, it
is believed to be worth considering its addition. Adding Authlib and refactoring
later, once they finish migrating to joserfc, is also a possibility

src/backend/pyproject.toml

@@ -47,6 +47,7 @@ dependencies = [
     "nested-multipart-parser==1.5.0",
     "psycopg[binary]==3.2.1",
     "PyJWT==2.9.0",
+    "joserfc==1.0.0",
     "requests==2.32.3",
     "sentry-sdk==2.13.0",
     "url-normalize==1.4.3",