chore: sync model pricing from OpenRouter API

providers/stepfun.toml

@@ -14,8 +14,8 @@ display_name = "Step 3.5 Flash"
 tier = "smart"
 context_window = 256000
 max_output_tokens = 256000
-input_cost_per_m = 0.0
-output_cost_per_m = 0.0
+input_cost_per_m = 0.1
+output_cost_per_m = 0.3
 supports_tools = true
 supports_vision = false
 supports_streaming = true
@@ -27,8 +27,8 @@ display_name = "Step 3"
 tier = "frontier"
 context_window = 65536
 max_output_tokens = 16384
-input_cost_per_m = 0.0
-output_cost_per_m = 0.0
+input_cost_per_m = 0.1
+output_cost_per_m = 0.3
 supports_tools = true
 supports_vision = true
 supports_streaming = true