[Dazzanova]

Summary

Preserve the current scroll position after successful action() and useForm submissions.

Previously, action submissions called router.visit() without setting preserveScroll, causing the page to scroll to the top after navigation.

This change:

• Defaults preserveScroll to true in the shared submitAction() function.
• Allows callers to explicitly disable scroll preservation with preserveScroll: false.
• Adds regression tests covering both default behavior and explicit overrides.
• Updates existing action-client tests to account for the new default.

Testing

• Local test suite passes.
• Added tests for default scroll preservation.
• Added test for explicitly disabling scroll preservation.

closes #700

[cpojer]

Thank you!