Python: Phase 2: Embedding clients for Ollama, Bedrock, and Azure AI Inference (#4207)

* Phase 2: Embedding clients for Ollama, Bedrock, and Azure AI Inference

Add embedding client implementations to existing provider packages:

- OllamaEmbeddingClient: Text embeddings via Ollama's embed API
- BedrockEmbeddingClient: Text embeddings via Amazon Titan on Bedrock
- AzureAIInferenceEmbeddingClient: Text and image embeddings via Azure AI
  Inference, supporting Content | str input with separate model IDs for
  text (AZURE_AI_INFERENCE_EMBEDDING_MODEL_ID) and image
  (AZURE_AI_INFERENCE_IMAGE_EMBEDDING_MODEL_ID) endpoints

Additional changes:
- Rename EmbeddingCoT -> EmbeddingT, EmbeddingOptionsCoT -> EmbeddingOptionsT
- Add otel_provider_name passthrough to all embedding clients
- Register integration pytest marker in all packages
- Add lazy-loading namespace exports for Ollama and Bedrock embeddings
- Add image embedding sample using Cohere-embed-v3-english
- Add azure-ai-inference dependency to azure-ai package

Part of #1188

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix mypy duplicate name and ruff lint issues

- Rename second 'vector' variable to 'img_vector' in image embedding loop
- Combine nested with statements in tests
- Remove unused result assignments in tests

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* updates from feedback

* Fix CI failures in embedding usage handling

- Fix Azure AI embedding mypy issues by normalizing vectors to list[float],
  safely accumulating optional usage token fields, and filtering None entries
  before constructing GeneratedEmbeddings
- Avoid Bandit false positive by initializing usage details as an empty dict
- Update OpenAI embedding tests to assert canonical usage keys
  (input_token_count/total_token_count)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/chatkit/pyproject.toml

@@ -36,6 +36,7 @@ environments = [
 
 [tool.uv-dynamic-versioning]
 fallback-version = "0.0.0"
+
 [tool.pytest.ini_options]
 testpaths = 'tests'
 addopts = "-ra -q -r fEX"
@@ -43,6 +44,9 @@ asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"
 filterwarnings = []
 timeout = 120
+markers = [
+    "integration: marks tests as integration tests that require external services",
+]
 
 [tool.ruff]
 extend = "../../pyproject.toml"
@@ -80,6 +84,7 @@ exclude_dirs = ["tests"]
 [tool.poe]
 executor.type = "uv"
 include = "../../shared_tasks.toml"
+
 [tool.poe.tasks]
 mypy = "mypy --config-file $POE_ROOT/pyproject.toml agent_framework_chatkit"
 test = "pytest --cov=agent_framework_chatkit --cov-report=term-missing:skip-covered tests"