Unit tests for IQ GPT Backend

[Softdev1]

We need to implement unit tests for various components of the IQ GPT Backend to ensure robustness and reliability. This issue focuses on setting up and writing unit tests for the following TypeScript files:

• src/core/domain/dataFilter/LLMDataFilter.ts
• src/core/domain/tool/DocumentSearch.ts
• src/core/domain/tool/APISearch.ts
• src/core/domain/endpointSelector/llmEndpointSelector/LLMEndpointSelector.ts
• src/core/domain/endpointSelector/vectorEndpointsSelector/VectorEndpointsSelector.ts
• src/core/domain/endpointSelector/EndpointSelector.ts
• src/core/domain/endpointSelector/enumFetcher/EnumFetcher.ts
• src/core/infrastructure/aiModels/GPT4O.ts
• src/core/infrastructure/tracer/LangfuseTracer.ts
• src/core/infrastructure/vectorDB/QdrantDB.ts

Tasks

• [x] Set up the testing environment for the project if not already in place.
• [x] Write unit tests for LLMDataFilter.ts.
• [x] Write unit tests for DocumentSearch.ts.
• [x] Write unit tests for APISearch.ts.
• [x] Write unit tests for LLMEndpointSelector.ts.
• [x] Write unit tests for EndpointSelector.ts.
• [x] Write unit tests for EnumFetcher.ts.
• [x] Write unit tests for LangfuseTracer.ts.
• [x] Write unit tests for QdrantDB.ts.
• [x] Write unit tests for SourceCollector.ts
• [x] Write unit tests for ToolManager.ts

[tommy39483]

For unit tests on the IQ GPT backend, focus on validating the accuracy of responses related to topics like celebrities IQ, ensuring consistent performance under various conditions, and checking integration with external data sources for reliability.