Standardize on job.id usage throughout the codebase

## Context

As part of the Jobs API migration (PR #7170), we're moving from legacy task structures to JobListItem-based data models. This issue tracks ensuring consistent usage of `job.id` throughout the codebase.

## Task

Review and update code to consistently use `job.id` directly rather than accessing through getters or indirect references where appropriate.

## Related

- PR: https://github.com/Comfy-Org/ComfyUI_frontend/pull/7170
- Comment: https://github.com/Comfy-Org/ComfyUI_frontend/pull/7170#discussion_r2651881851
- Requested by: @christian-byrne

## Notes

This is a follow-up task from the Jobs API migration to improve code consistency and maintainability.

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-7954-Standardize-on-job-id-usage-throughout-the-codebase-2e56d73d365081afb03dfebfd843e9bd) by [Unito](https://www.unito.io)