fix: remove lastActionType from execution state

[effie-ms]

Which Linear task is linked to this PR?

https://linear.app/lifi-linear/issue/EMB-310/bug-execution-status-failed-but-no-action-marked-failed-on-reload

Why was it implemented this way?

On retry after a failed step (e.g. RECEIVING_CHAIN wait-for-status), a subsequent failure set execution.status to FAILED without marking any action as FAILED, so the UI had no indication of which action failed.

Causes:

• Error handling in BaseStepExecutor only marked an action as FAILED when it could resolve it via step.execution.lastActionType.
• lastActionType was cleared in prepareRestart and in StatusManager.initializeExecution when resuming from FAILED, so the catch had no action to update.

Solution: Since actions are added and updated in the order of creation, use the last action in execution.actions as the failing action and remove lastActionType from the codebase.

Why: Single source of truth (pipeline order = last element is current). The bug came from lastActionType being cleared in multiple places while the actions array held the real state; removing the field removes that type of bugs. After prepareRestart, the last element is the action we're retrying, so marking it FAILED is correct. Alternative was to set/preserve lastActionType in prepareRestart and init, deriving from the array was chosen to avoid redundant state and keep a single source of truth.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.