Move EmbeddingClient into openai.py and remove separate file

- Move EmbeddingClient class and EmbeddingError from embedding_client.py to openai.py
- Update analyzer.py to import EmbeddingClient from openai module
- Delete ai/embedding_client.py (no longer needed)
- All embedding functionality now consolidated in openai.py
- get_embedding_for_text remains in openai.py (can be used for backward compatibility)

Co-authored-by: Mte90 <403283+Mte90@users.noreply.github.com>

Author: Copilot

ai/analyzer.py

@@ -18,8 +18,7 @@
     search_vectors as _search_vectors,
     get_chunk_text as _get_chunk_text,
 )
-from .openai import call_coding_api
-from .embedding_client import EmbeddingClient
+from .openai import call_coding_api, EmbeddingClient
 from llama_index.core import Document
 from utils.logger import get_logger
 from utils import compute_file_hash, chunk_text, norm, cosine