client-sdk: add templates and server fixes

Complete the SDK template suite and fix related server/test issues:

Template Additions:
- Add _exceptions.mustache, _types.mustache, _version.mustache
- Update README templates with hierarchical API examples
- Enhance configuration.mustache with better defaults
- Update partial templates for consistency

Server Fixes:
- Fix error response format to match OpenAPI spec (remove wrapper)
- Update library_client for new SDK structure

Test Updates:
- Update integration tests to use new LlamaStackClient
- Fix imports and client initialization patterns
- Update embeddings, rerank, tools, and vector_io tests

Stainless Config:
- Update config for compatibility with OpenAPI Generator output

These changes complete the migration to the hierarchical SDK structure
while maintaining backward compatibility.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: aegeiger

client-sdks/openapi/templates/python/README.mustache

@@ -58,4 +58,3 @@ Execute `pytest` to run the tests.
 Please follow the [installation procedure](#installation--usage) and then run the following:
 
 {{> common_README }}
-

client-sdks/openapi/templates/python/README_onlypackage.mustache

@@ -48,4 +48,3 @@ In your own code, to use this library to connect and interact with {{{projectNam
 you can run the following:
 
 {{> common_README }}
-

client-sdks/openapi/templates/python/_exceptions.mustach

@@ -0,0 +1,114 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+# File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+from __future__ import annotations
+
+from typing_extensions import Literal
+
+import httpx
+
+__all__ = [
+    "BadRequestError",
+    "AuthenticationError",
+    "PermissionDeniedError",
+    "NotFoundError",
+    "ConflictError",
+    "UnprocessableEntityError",
+    "RateLimitError",
+    "InternalServerError",
+]
+
+
+class LlamaStackClientError(Exception):
+    pass
+
+
+class APIError(LlamaStackClientError):
+    message: str
+    request: httpx.Request
+
+    body: object | None
+    """The API response body.
+
+    If the API responded with a valid JSON structure then this property will be the
+    decoded result.
+
+    If it isn't a valid JSON structure then this will be the raw response.
+
+    If there was no response associated with this error then it will be `None`.
+    """
+
+    def __init__(self, message: str, request: httpx.Request, *, body: object | None) -> None:  # noqa: ARG002
+        super().__init__(message)
+        self.request = request
+        self.message = message
+        self.body = body
+
+
+class APIResponseValidationError(APIError):
+    response: httpx.Response
+    status_code: int
+
+    def __init__(self, response: httpx.Response, body: object | None, *, message: str | None = None) -> None:
+        super().__init__(message or "Data returned by API invalid for expected schema.", response.request, body=body)
+        self.response = response
+        self.status_code = response.status_code
+
+
+class APIStatusError(APIError):
+    """Raised when an API response has a status code of 4xx or 5xx."""
+
+    response: httpx.Response
+    status_code: int
+
+    def __init__(self, message: str, *, response: httpx.Response, body: object | None) -> None:
+        super().__init__(message, response.request, body=body)
+        self.response = response
+        self.status_code = response.status_code
+
+
+class APIConnectionError(APIError):
+    def __init__(self, *, message: str = "Connection error.", request: httpx.Request) -> None:
+        super().__init__(message, request, body=None)
+
+
+class APITimeoutError(APIConnectionError):
+    def __init__(self, request: httpx.Request) -> None:
+        super().__init__(message="Request timed out.", request=request)
+
+
+class BadRequestError(APIStatusError):
+    status_code: Literal[400] = 400  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class AuthenticationError(APIStatusError):
+    status_code: Literal[401] = 401  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class PermissionDeniedError(APIStatusError):
+    status_code: Literal[403] = 403  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class NotFoundError(APIStatusError):
+    status_code: Literal[404] = 404  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class ConflictError(APIStatusError):
+    status_code: Literal[409] = 409  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class UnprocessableEntityError(APIStatusError):
+    status_code: Literal[422] = 422  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class RateLimitError(APIStatusError):
+    status_code: Literal[429] = 429  # pyright: ignore[reportIncompatibleVariableOverride]
+
+
+class InternalServerError(APIStatusError):
+    pass