## Description
Adds spec file and fixture file for on page unload functionality
Fixes#41000
_or_
Fixes `Issue URL`
> [!WARNING]
> _If no issue exists, please create an issue first, and check with the
maintainers if the issue is valid._
## Automation
/ok-to-test tags="@tag.JS, @tag.Sanity"
### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results -->
> [!TIP]
> 🟢🟢🟢 All cypress tests have passed! 🎉🎉🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/16070917983>
> Commit: 9435c88d922a2c1344cc5feb955ce3eb5f8620f5
> <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=16070917983&attempt=1"
target="_blank">Cypress dashboard</a>.
> Tags: `@tag.JS, @tag.Sanity`
> Spec:
> <hr>Fri, 04 Jul 2025 10:45:13 UTC
<!-- end of auto-generated comment: Cypress test results -->
## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [ ] No
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Tests**
* Added a comprehensive end-to-end test suite to verify on-page unload
behavior across different application modes and navigation methods.
* Included scenarios to ensure unload handlers trigger correctly and do
not fire redundantly.
* Confirmed execution of multiple unload handlers in preview mode.
* **Chores**
* Introduced a new application fixture for testing on-page unload
actions with multiple pages, widgets, and JavaScript actions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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