Tracing scopes don't interact well with App::Run()

## Bevy version and features

- 0.16.1

## What you did

Ran this
```
fn f() {
info!("Hello, world!");
}

fn main() {
let mut app = App::new();
app.add_plugins(DefaultPlugins);

app.add_systems(Update, f);
info_span!("hi").in_scope(|| app.run());
}
```

## What went wrong

I would expect "hi" to be added to every log line, but I get:
```
2025-08-30T13:55:45.800802Z INFO hi: bevy_render::batching::gpu_preprocessing: GPU preprocessing is fully supported on this device.
2025-08-30T13:55:45.978609Z INFO hi: bevy_winit::system: Creating new window empty (0v0)
2025-08-30T13:55:46.007255Z INFO empty: Hello, world!
2025-08-30T13:55:46.437210Z INFO empty: Hello, world!
2025-08-30T13:55:48.766013Z INFO empty: Hello, world!
...
2025-08-30T13:55:51.559464Z INFO empty: Hello, world!
2025-08-30T13:55:51.559788Z INFO bevy_window::system: No windows are open, exiting
2025-08-30T13:55:51.560534Z INFO hi: bevy_winit::system: Closing window 0v0
```

"hi" is added to app internal behaviour but not to logs happening inside systems.

Reproduce the supplied Rust example on Bevy 0.16.1, starting with App::run and the system execution path. Trace how the info_span!("hi") scope is propagated into app internals versus systems, then verify that logs from f retain the hi span while preserving the surrounding log behavior.

Written by the indexing model from the issue text.