[Bug] Updating select mode after instantiation, removes its previous settings.

[RLaipins]

Describe the bug
After trying to update snapping behavior of polygon when selected it resets the previous flags/settings.

Terra Draw npm version
terradraw - 1.24.0,
Maplibre adapter - 1.3.0

To Reproduce
Steps to reproduce the behavior:

1. Have terradraw initated with snappable:true for select mode or any other flags
2. Have at least 2 polygons drawn (in this case)
3. Enter select mode and select 1 polygon
4. Try to snap it to other polygon
5. Update select mode options programmatically

this.draw?.updateModeOptions<typeof TerraDrawSelectMode>('select', {
      flags: {
        polygon: {
          feature: {
            coordinates: { snappable: false },
          },
        },
      },
    });

6. See it reset to default flags

Expected behavior

It would take partial updates just how the regular polygon/linestring mode updates work after instantiation without the need to track previous state.

Screenshots
If applicable, add screenshots to help explain your problem.

2026-03-30.16-34-09.mp4

Desktop (please complete the following information):

• OS: Linux mint
• Browser: Chrome
• Version: 146.0.7680.164

Additional context