refactor(platform): restructure platform-specific abstractions and add synthetic backends

build.rs

@@ -12,5 +12,15 @@ fn main() {
         );
     }
 
+    match target_os.as_str() {
+        "linux" => {}
+        "macos" => println!(
+            "cargo::warning=traffic control is unavailable on macOS; requested rate changes will be calculated but not applied"
+        ),
+        _ => println!(
+            "cargo::warning=target `{target}` has no native interface-statistics or traffic-control backend; synthetic interface load will be used and requested rate changes will not be applied"
+        ),
+    }
+
     println!("cargo::rerun-if-changed=build.rs");
 }