test: cover critical regression paths

[vibhor1102]

Summary

Adds regression coverage for critical paths across gesture execution, database migrations, scenario backup import, counters, actions, conditions, events, and scenario editing.

The branch targets dev-4.0.0-beta08-fixes and contains the test commit only. The temporary hosted verification workflow used during validation was removed before opening this PR.

Findings from verification

The hosted verification run executed the independent test tasks and exposed four failures. The tests appear valid and are intentionally left unfixed for maintainer review:

• A late gesture callback can complete the next gesture after a timeout.
• Migration 19 to 20 does not actually process lowercase persisted enum values despite normalizing them in Kotlin.
• Current-version smart backup imports reject unknown nested fields despite the forward-compatibility intent.
• The counter creation command can add a whitespace-only counter when called directly, although the normal UI disables Save.

These findings are tracked in #1046. This PR adds the regression tests only; production fixes are intentionally left for separate maintainer follow-up.

Validation

Hosted verify run: https://github.com/vibhor1102/Smart-AutoClicker/actions/runs/31606697584

The run used the temporary verify-only workflow and reported the four test failures above. No local Gradle tests were run because repository guidance prohibits local compilation/testing on this machine.