Say hello world and fix IAuthenticationBackend interface compliance

[smartin-qb]

Summary

• Add hello_world.py that prints "Hello World"
• Fix erroneous self parameter in IAuthenticationBackend.handle_authentication interface definition (zope.interface methods must not include self)
• Add handle_authentication no-op default to _BaseAuthBackend so all subclasses satisfy the interface contract

Assumptions

• The handle_authentication method was missing from several auth backend classes (pre-existing bug); added it to the base class as a no-op so all subclasses inherit it
• 7 integration tests remain failing due to Python 3.12 asyncio event-loop compatibility issues (pre-existing, unrelated to this change)

Test plan

• All 6 auth interface verification tests now pass (previously all 13 auth tests were failing)
• test_rpc_registry and test_serialization pass
• Integration tests require Python 3.7 event loop compatibility fixes (pre-existing issue)

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Created by QBee autonomous agent (session: TEST-NULL51)