[tests] add client-sdk pytests & delete client.py (#638)

# What does this PR do?

**Why**
- Clean up examples which we will not maintain; reduce the surface area
to the minimal showcases

**What**
- Delete `client.py` in /apis/*
- Move all scripts to unit tests
  - SDK sync in the future will just require running pytests

**Side notes**
- `bwrap` not available on Mac so code_interpreter will not work

## Test Plan

```
LLAMA_STACK_BASE_URL=http://localhost:5000 pytest -v ./tests/client-sdk
```
<img width="725" alt="image"
src="https://github.com/user-attachments/assets/36bfe537-628d-43c3-8479-dcfcfe2e4035"
/>


## Sources

Please link relevant resources if necessary.


## Before submitting

- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
- [ ] Ran pre-commit to handle lint / formatting issues.
- [ ] Read the [contributor
guideline](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

tests/client-sdk/inference/test_inference.py

@@ -0,0 +1,74 @@
+# 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.
+
+import pytest
+from llama_stack_client.lib.inference.event_logger import EventLogger
+
+
+def test_text_chat_completion(llama_stack_client):
+    # non-streaming
+    available_models = [
+        model.identifier
+        for model in llama_stack_client.models.list()
+        if model.identifier.startswith("meta-llama")
+    ]
+    assert len(available_models) > 0
+    model_id = available_models[0]
+    response = llama_stack_client.inference.chat_completion(
+        model_id=model_id,
+        messages=[
+            {
+                "role": "user",
+                "content": "Hello, world!",
+            }
+        ],
+        stream=False,
+    )
+    assert len(response.completion_message.content) > 0
+
+    # streaming
+    response = llama_stack_client.inference.chat_completion(
+        model_id=model_id,
+        messages=[{"role": "user", "content": "Hello, world!"}],
+        stream=True,
+    )
+    logs = [str(log.content) for log in EventLogger().log(response) if log is not None]
+    assert len(logs) > 0
+    assert "Assistant> " in logs[0]
+
+
+def test_image_chat_completion(llama_stack_client):
+    available_models = [
+        model.identifier
+        for model in llama_stack_client.models.list()
+        if "vision" in model.identifier.lower()
+    ]
+    if len(available_models) == 0:
+        pytest.skip("No vision models available")
+
+    model_id = available_models[0]
+    # non-streaming
+    message = {
+        "role": "user",
+        "content": [
+            {
+                "image": {
+                    "uri": "https://www.healthypawspetinsurance.com/Images/V3/DogAndPuppyInsurance/Dog_CTA_Desktop_HeroImage.jpg"
+                }
+            },
+            "Describe what is in this image.",
+        ],
+    }
+    response = llama_stack_client.inference.chat_completion(
+        model_id=model_id,
+        messages=[message],
+        stream=False,
+    )
+    assert len(response.completion_message.content) > 0
+    assert (
+        "dog" in response.completion_message.content.lower()
+        or "puppy" in response.completion_message.content.lower()
+    )