fix: resolve type hint issues and import dependencies (#1176)

# What does this PR do?

- Fixed type hinting and missing imports across multiple modules.
- Improved compatibility by using `TYPE_CHECKING` for conditional
imports.
- Updated `pyproject.toml` to enforce stricter linting.

Signed-off-by: Sébastien Han <seb@redhat.com>

Signed-off-by: Sébastien Han <seb@redhat.com>

llama_stack/providers/tests/post_training/test_post_training.py

@@ -3,6 +3,8 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
+from typing import List
+
 import pytest
 
 from llama_stack.apis.common.job_types import JobStatus