fix: prevent silent discard of event/task edits

[naveensingh]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

Applied the same fix as FossifyOrg/Contacts#362 in both event and task editors. Some edits are still being discarded due to #49, which I will address in another PR soon.

Tests performed

• Back navigation using the arrow button after editing events/tasks

Closes the following issue(s)

• Closes Ask for confirmation when pressing in-app 'back' button during adding/editing an event #803

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• All checks are passing.