`symbol` layers using `symbol-placement: line` render above `line` layers at zoom < 13.7 in Mapbox Standard

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### mapbox-gl-js version

3.28.0

### Browser and version

Chrome 151.0.7922.75

### Expected behavior

A `line` layer added **after** a `symbol` layer (intended to render on top) should remain visually above the symbols at all zoom levels.

### Actual behavior

When zooming out past ~13.7 in Mapbox Standard, `symbol` layers placed along lines are hoisted into a top-level overlay pass, rendering directly on top of `line` layers regardless of `beforeId`, `slot`, or execution order.

### Link to the demonstration

_No response_

### Steps to trigger the unexpected behavior

1. Load Mapbox GL JS (latest v3 release) with `mapbox://styles/mapbox/standard`.
2. Add a `symbol` layer (`planned-dots`) with `symbol-placement: "line"` along a LineString.
3. Add a `line` layer (`route-line`) on top of `planned-dots` (e.g. `map.addLayer(routeLine)` called after `planned-dots`).
4. Observe correct z-ordering at zoom > 14 (`route-line` covers `planned-dots`).
5. Zoom out past 13.7 and observe `planned-dots` hopping on top of `route-line`.

```javascript
// 1. Add Planned Dots (Symbol Layer - rendered first/below)
map.addLayer({
id: 'planned-dots',
type: 'symbol',
source: 'route-source',
layout: {
'symbol-placement': 'line',
'symbol-spacing': 20,
'icon-image': 'dot-icon',
'icon-allow-overlap': true,
'icon-ignore-placement': true
}
});

// 2. Add Route Line (Line Layer - added second to render ON TOP of dots)
map.addLayer({
id: 'route-line',
type: 'line',
source: 'route-source',
paint: {
'line-color': '#2a82e4',
'line-width': 8
}
}); // Drawn after planned-dots to sit on top

### Relevant log output

```shell

```

Reproduce the issue with map.addLayer using the provided planned-dots and route-line layers, Mapbox Standard, and zooming across 13.7. Trace how symbol layers with symbol-placement: line are rendered relative to line layers and verify that beforeId, slot, and execution order remain effective at every zoom level.

Written by the indexing model from the issue text.