Refactored, added comprehensive testing.

api/testdata/ollama_no_response.json

@@ -0,0 +1,3 @@
+{
+  "model": "llama3"
+}

api/testdata/ollama_success.json

@@ -0,0 +1,3 @@
+{
+  "response": "This is the Ollama response."
+}

api/testdata/openai_empty_choices.json

@@ -0,0 +1,3 @@
+{
+  "choices": []
+}

api/testdata/openai_success.json

@@ -0,0 +1,9 @@
+{
+  "choices": [
+    {
+      "message": {
+        "content": "This is the response text."
+      }
+    }
+  ]
+}