Add Perplexity Sonar to free models

app.py

@@ -27,6 +27,7 @@ FREE_MODEL_CHOICES = [
     "gpt-4o",
     "mistral-medium-latest",
     "claude-3-haiku-20240307",
+    "sonar",
 ]
 
 # Paid models (user provides their own API key)
@@ -130,6 +131,10 @@ def classify_data(spreadsheet_file, spreadsheet_column,
             actual_api_key = os.environ.get("ANTHROPIC_API_KEY", "")
             if not actual_api_key:
                 return None, None, "**Error:** Anthropic API key not configured in Space secrets"
+        elif "sonar" in model.lower():
+            actual_api_key = os.environ.get("PERPLEXITY_API_KEY", "")
+            if not actual_api_key:
+                return None, None, "**Error:** Perplexity API key not configured in Space secrets"
         else:
             actual_api_key = os.environ.get("HF_API_KEY", "")
     else: