use per-user runtime stats path for reliable gsfd+tui updates

crates/core/src/inputspeed.rs

@@ -44,6 +44,11 @@ fn stats_path() -> PathBuf {
         return PathBuf::from(path);
     }
 
-    // Keep default shared across sudo/non-sudo runs.
+    if let Ok(runtime_dir) = std::env::var("XDG_RUNTIME_DIR")
+        && !runtime_dir.is_empty()
+    {
+        return PathBuf::from(runtime_dir).join("gsf-speed.txt");
+    }
+
     PathBuf::from("/tmp/gsf-speed.txt")
 }