feat: Add FAISS search tool

- Implement FAISSSearchTool for vector similarity search
- Add comprehensive unit tests
- Update documentation with usage examples
- Add FAISS dependency

Closes #2118

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/tools/test_faiss_search_tool.py

@@ -0,0 +1,43 @@
+import pytest
+import numpy as np
+from crewai.tools import FAISSSearchTool
+
+def test_faiss_search_tool_initialization():
+    tool = FAISSSearchTool()
+    assert tool.name == "FAISS Search Tool"
+    assert tool.dimension == 384
+
+def test_faiss_search_with_texts():
+    tool = FAISSSearchTool()
+    texts = [
+        "The quick brown fox",
+        "jumps over the lazy dog",
+        "A completely different text"
+    ]
+    tool.add_texts(texts)
+    
+    results = tool.run(
+        query="quick fox",
+        k=2,
+        score_threshold=0.5
+    )
+    
+    assert len(results) > 0
+    assert isinstance(results[0]["text"], str)
+    assert isinstance(results[0]["score"], float)
+
+def test_faiss_search_threshold_filtering():
+    tool = FAISSSearchTool()
+    texts = ["Text A", "Text B", "Text C"]
+    tool.add_texts(texts)
+    
+    results = tool.run(
+        query="Something completely different",
+        score_threshold=0.99  # High threshold
+    )
+    
+    assert len(results) == 0  # No results above threshold
+
+def test_invalid_index_type():
+    with pytest.raises(ValueError):
+        FAISSSearchTool(index_type="INVALID")