Issue 3890 Tool call results returned via ChatResponse lack identification metadata

[wilocu]

#3890
Summary
This PR adds the ability to distinguish between model-generated and tool-generated responses in OllamaChatModel by adding source metadata to
ChatResponse objects. Frontend developers can now easily identify the origin of each response through standardized metadata fields.

Changes Made
Core Implementation:

• OllamaChatModel.java: Added source metadata constants and modified internalStream() and internalCall() methods to include source="model" in
  generation metadata
• ToolExecutionResult.java: Added source metadata constants and enhanced buildGenerations() to include source="tool" for tool-generated
  responses

Testing:

• OllamaChatModelTests.java: Added unit test to verify source metadata creation
• ToolExecutionResultTests.java: Added unit test to verify tool response source metadata
• OllamaChatModelIT.java: Added integration test to verify source metadata in real responses

Usage
Developers can now identify response sources:
ChatResponse response = chatModel.call(new Prompt("Hello"));
String source = (String) response.getResult().getMetadata().get("source");
// Returns: "model" for model-generated responses
// Returns: "tool" for tool-generated responses

Testing

• All existing tests continue to pass
• New unit tests verify metadata creation for both model and tool responses
• Integration test confirms functionality with real Ollama responses
• Build passes with ./mvnw clean package -DskipTests on modified modules

This implementation provides a clean, maintainable solution that enables frontend developers to easily differentiate between response sources
while maintaining full backward compatibility.

Signed-off-by: Mattia Pasetto matpat17@gmail.com

I am still pretty new to contributions, please double check and let me know of any errors.