fix(scan): respect global evaluation result for accepted risks

[tembleking]

This PR fixes a regression introduced in v6.2.0 where the action would fail even if all risks were accepted and the global policy evaluation passed.

The ScanResult domain entity was incorrectly recalculating the final evaluation result based on the outcome of individual policies, ignoring the global evaluation result provided in the scanner's report.
This was wrong because the accepted risk at the level of an image is not reflected in the policy evaluations.
This caused the action to fail when stop-on-failed-policy-eval was set to true.

This has been fixed by:

• Storing the globalEvaluation from the report directly in the ScanResult.
• Ensuring this global result is used to determine the final action status.
• Adding a test case with a fixture where risks are globally accepted to prevent future regressions.

Fixes #92

[alecron]

LGTM