feat: split API and provider specs into separate llama-stack-api pkg

Extract API definitions, models, and provider specifications into a
standalone llama-stack-api package that can be published to PyPI
independently of the main llama-stack server.

Motivation

External providers currently import from llama-stack, which overrides
the installed version and causes dependency conflicts. This separation
allows external providers to:

- Install only the type definitions they need without server dependencies
- Avoid version conflicts with the installed llama-stack package
- Be versioned and released independently

This enables us to re-enable external provider module tests that were
previously blocked by these import conflicts.

Changes

- Created llama-stack-api package with minimal dependencies (pydantic, jsonschema)
- Moved APIs, providers datatypes, strong_typing, and schema_utils
- Updated all imports from llama_stack.* to llama_stack_api.*
- Preserved git history using git mv for moved files
- Configured local editable install for development workflow
- Updated linting and type-checking configuration for both packages
- Rebased on top of upstream src/ layout changes

Testing

Package builds successfully and can be imported independently.
All pre-commit hooks pass with expected exclusions maintained.

Next Steps

- Publish llama-stack-api to PyPI
- Update external provider dependencies
- Re-enable external provider module tests

Signed-off-by: Charlie Doern <cdoern@redhat.com>

tests/unit/utils/inference/test_inference_store.py

@@ -7,14 +7,14 @@
 import time
 
 import pytest
-
-from llama_stack.apis.inference import (
+from llama_stack_api.apis.inference import (
     OpenAIAssistantMessageParam,
     OpenAIChatCompletion,
     OpenAIChoice,
     OpenAIUserMessageParam,
     Order,
 )
+
 from llama_stack.core.storage.datatypes import InferenceStoreReference, SqliteSqlStoreConfig
 from llama_stack.providers.utils.inference.inference_store import InferenceStore
 from llama_stack.providers.utils.sqlstore.sqlstore import register_sqlstore_backends

tests/unit/utils/responses/test_responses_store.py

@@ -9,13 +9,13 @@ from tempfile import TemporaryDirectory
 from uuid import uuid4
 
 import pytest
-
-from llama_stack.apis.agents import Order
-from llama_stack.apis.agents.openai_responses import (
+from llama_stack_api.apis.agents import Order
+from llama_stack_api.apis.agents.openai_responses import (
     OpenAIResponseInput,
     OpenAIResponseObject,
 )
-from llama_stack.apis.inference import OpenAIMessageParam, OpenAIUserMessageParam
+from llama_stack_api.apis.inference import OpenAIMessageParam, OpenAIUserMessageParam
+
 from llama_stack.core.storage.datatypes import ResponsesStoreReference, SqliteSqlStoreConfig
 from llama_stack.providers.utils.responses.responses_store import ResponsesStore
 from llama_stack.providers.utils.sqlstore.sqlstore import register_sqlstore_backends
@@ -46,7 +46,7 @@ def create_test_response_object(
 
 def create_test_response_input(content: str, input_id: str) -> OpenAIResponseInput:
     """Helper to create a test response input."""
-    from llama_stack.apis.agents.openai_responses import OpenAIResponseMessage
+    from llama_stack_api.apis.agents.openai_responses import OpenAIResponseMessage
 
     return OpenAIResponseMessage(
         id=input_id,