test: add tests for embeddings module (blackbox)

[ismaeldouglasdev]

Add missing test coverage for the embeddings module.

The embeddings.py handles embedding generation for semantic search. Currently has no test file.

Why

• Test embedding generation with known inputs
• Verify sentence-transformers integration
• Test error handling for invalid models

Suggested tests

• test_generate_embedding_text
• test_generate_embedding_empty
• test_generate_embedding_invalid_model

[ismaeldouglasdev]

Hey! I'd like to work on this issue. Please assign me (@ismaeldouglasdev).