Separator: fixes memory leakes

- Add missing ffStrbufDestroy(&options->outputColor) in ffDestroySeparatorOptions
  to prevent memory leak when outputColor is set via JSON config
- Replace two exit(1) calls in ffPreparePublicIp with proper error status
  propagation, matching the pattern used in the weather module

src/modules/separator/separator.c

@@ -117,6 +117,7 @@ void ffInitSeparatorOptions(FFSeparatorOptions* options) {
 
 void ffDestroySeparatorOptions(FFSeparatorOptions* options) {
     ffStrbufDestroy(&options->string);
+    ffStrbufDestroy(&options->outputColor);
 }
 
 FFModuleBaseInfo ffSeparatorModuleInfo = {