Refactor embedding logic to shared utility to fix circular dependency

[ishaanxgupta]

Extracted embed_text logic from src/pipelines/ingest.py to src/utils/embeddings.py to resolve circular dependency with src/storage/pinecone.py.

Changes:

• Created src/utils/embeddings.py with embed_text and get_embedding_client.
• Updated src/pipelines/ingest.py, src/storage/pinecone.py, and src/pipelines/retrieval.py to use the new utility.
• Added tests/unit/utils/test_embeddings.py to verify the new utility.
• Verified all changes with ruff and unit tests.

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PR created automatically by Jules for task 7571175948543949607 started by @ishaanxgupta

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