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/loader.go

@@ -73,6 +73,10 @@ func defaultConfig() Config {
 				Model:       "gpt-4o-mini",
 				Temperature: 0.1,
 			},
+			Ollama: OllamaConfig{
+				BaseURL: "http://localhost:11434/v1",
+				APIKey:  "ollama",
+			},
 		},
 		Capture: CaptureConfig{
 			Source: DefaultSource,
@@ -97,6 +101,8 @@ func applyEnvOverrides(cfg *Config) {
 	overrideString(&cfg.Database.URL, "OB1_DATABASE_URL")
 	overrideString(&cfg.AI.LiteLLM.BaseURL, "OB1_LITELLM_BASE_URL")
 	overrideString(&cfg.AI.LiteLLM.APIKey, "OB1_LITELLM_API_KEY")
+	overrideString(&cfg.AI.Ollama.BaseURL, "OB1_OLLAMA_BASE_URL")
+	overrideString(&cfg.AI.Ollama.APIKey, "OB1_OLLAMA_API_KEY")
 	overrideString(&cfg.AI.OpenRouter.APIKey, "OB1_OPENROUTER_API_KEY")
 
 	if value, ok := os.LookupEnv("OB1_SERVER_PORT"); ok {