refactor: remove unused contentToText helper from Ollama driver (#17639)

internal/entity/models/ollama.go

@@ -33,26 +33,6 @@ type OllamaModel struct {
 	baseModel BaseModel
 }
 
-// contentToText extracts a plain-text string from a Message.Content value.
-// Content may be a raw string or an OpenAI-style multimodal array
-// ([]interface{} where each element is {"type": "text", "text": "..."}).
-// The first non-empty "text" value found is returned; empty string on no match.
-func contentToText(content interface{}) string {
-	switch c := content.(type) {
-	case string:
-		return c
-	case []interface{}:
-		for _, item := range c {
-			if part, ok := item.(map[string]interface{}); ok {
-				if text, ok := part["text"].(string); ok && text != "" {
-					return text
-				}
-			}
-		}
-	}
-	return ""
-}
-
 // NewOllamaModel creates a new Ollama AI model instance
 func NewOllamaModel(baseURL map[string]string, urlSuffix URLSuffix) *OllamaModel {
 	return &OllamaModel{