Fix CI issues: remove unused imports in test files and update CI workflow to only check project-specific files

tests/test_embeddings.py

@@ -1,4 +1,3 @@
-import pytest
 import numpy as np
 
 from shell_history_search.core import EmbeddingService
@@ -87,4 +86,4 @@ class TestEmbeddingService:
         e1 = service.encode_single("same command")
 
         sim = EmbeddingService.cosine_similarity(e1, e1)
-        assert 0.9999 < sim <= 1.0001
+        assert 0.9999 < sim <= 1.0001