Added support for the service_tier key in profiles

internal/llm/openai_compatible_client_test.go

@@ -61,6 +61,7 @@ func TestOpenAICompatibleClientGenerateSuccess(t *testing.T) {
 			Temperature: 0.4,
 			MaxTokens:   123,
 			TopP:        0.7,
+			ServiceTier: "priority",
 			APIKeyEnv:   "SCRIPTORIUM_TEST_API_KEY",
 		},
 		StructuredOutput: &domain.StructuredOutputSpec{
@@ -95,6 +96,9 @@ func TestOpenAICompatibleClientGenerateSuccess(t *testing.T) {
 	if got, ok := obs.Body["model"].(string); !ok || got != "gpt-test" {
 		t.Fatalf("unexpected model payload: %#v", obs.Body["model"])
 	}
+	if got, ok := obs.Body["service_tier"].(string); !ok || got != "priority" {
+		t.Fatalf("unexpected service_tier payload: %#v", obs.Body["service_tier"])
+	}
 
 	msgs, ok := obs.Body["messages"].([]any)
 	if !ok || len(msgs) != 2 {
@@ -157,6 +161,9 @@ func TestOpenAICompatibleClientOmitsResponseFormatWhenNoStructuredOutput(t *test
 	if _, exists := observedBody["response_format"]; exists {
 		t.Fatalf("expected response_format omitted, got %#v", observedBody["response_format"])
 	}
+	if _, exists := observedBody["service_tier"]; exists {
+		t.Fatalf("expected service_tier omitted, got %#v", observedBody["service_tier"])
+	}
 }
 
 func TestOpenAICompatibleClientNoAuthorizationHeaderWhenNoAPIKey(t *testing.T) {