feat: add configurable search parameters for RAG, knowledge, and memory (#3531)

- Add limit and score_threshold to BaseRagConfig, propagate to clients  
- Update default search params in RAG storage, knowledge, and memory (limit=5, threshold=0.6)  
- Fix linting (ruff, mypy, PERF203) and refactor save logic  
- Update tests for new defaults and ChromaDB behavior

src/crewai/knowledge/knowledge.py

@@ -43,7 +43,7 @@ class Knowledge(BaseModel):
         self.sources = sources
 
     def query(
-        self, query: list[str], results_limit: int = 3, score_threshold: float = 0.35
+        self, query: list[str], results_limit: int = 5, score_threshold: float = 0.6
     ) -> list[SearchResult]:
         """
         Query across all knowledge sources to find the most relevant information.