feat(ai): add support for Ollama AI provider configuration

* Update README with Ollama integration details
* Add Ollama configuration to example YAML files
* Implement Ollama provider in AI factory
* Add tests for Ollama provider functionality
* Enhance config validation for Ollama settings

internal/config/validate_test.go

@@ -19,6 +19,10 @@ func validConfig() Config {
 				BaseURL: "http://localhost:4000/v1",
 				APIKey:  "key",
 			},
+			Ollama: OllamaConfig{
+				BaseURL: "http://localhost:11434/v1",
+				APIKey:  "ollama",
+			},
 			OpenRouter: OpenRouterAIConfig{
 				BaseURL: "https://openrouter.ai/api/v1",
 				APIKey:  "key",
@@ -29,12 +33,17 @@ func validConfig() Config {
 	}
 }
 
-func TestValidateAcceptsLiteLLMAndOpenRouter(t *testing.T) {
+func TestValidateAcceptsSupportedProviders(t *testing.T) {
 	cfg := validConfig()
 	if err := cfg.Validate(); err != nil {
 		t.Fatalf("Validate litellm error = %v", err)
 	}
 
+	cfg.AI.Provider = "ollama"
+	if err := cfg.Validate(); err != nil {
+		t.Fatalf("Validate ollama error = %v", err)
+	}
+
 	cfg.AI.Provider = "openrouter"
 	if err := cfg.Validate(); err != nil {
 		t.Fatalf("Validate openrouter error = %v", err)