* fix: implement lazy client creation in replicate.use()

Fixes issue where replicate.use() would fail if no API token was available at call time,
even when token becomes available later (e.g., from cog.current_scope).

Changes:
- Modified Function/AsyncFunction classes to accept client factories
- Added _client property that creates client on demand
- Updated module client to pass factory functions instead of instances
- Token is now retrieved from current scope when model is called

This maintains full backward compatibility while enabling use in Cog pipelines
where tokens are provided through the execution context.

* style: fix linter issues

- Remove unused *args parameter in test function
- Fix formatting issues from linter

* fix: resolve async detection and test issues

- Fix async detection to not call client factory prematurely
- Add use_async parameter to explicitly indicate async mode
- Update test to avoid creating client during verification
- Fix test mocking to use correct module path

* test: simplify lazy client test

Replace complex mocking test with simpler verification that:
- use() works without token initially
- Lazy client factory is properly configured
- Client can be created when needed

This avoids complex mocking while still verifying the core functionality.

* lint

* fix: add type ignore for final linter warning

* fix: add arg-type ignore for type checker warnings

* refactor: simplify lazy client creation to use Type[Client] only

Address PR feedback by removing Union types and using a single consistent approach:

- Change Function/AsyncFunction constructors to accept Type[Client] only
- Remove Union[Client, Type[Client]] in favor of just Type[Client]
- Simplify _client property logic by removing isinstance checks
- Update all use() overloads to accept class types only
- Use issubclass() for async client detection instead of complex logic
- Update tests to check for _client_class attribute

This maintains the same lazy client creation behavior while being
much simpler and more consistent.

* Update tests/test_simple_lazy.py

Co-authored-by: Aron Carroll <[email protected]>

* test: improve lazy client test to follow project conventions

- Remove verbose comments and print statements
- Focus on observable behavior rather than internal implementation
- Use proper mocking that matches actual cog integration
- Test that cog.current_scope() is called on client creation
- Address code review feedback from PR discussion

* lint

* lint

---------

Co-authored-by: Aron Carroll <[email protected]>