Login refactor - brought back recent changes

[trtshen]

This pull request updates accessibility documentation and assessment flow documentation to clarify and improve descriptions of WCAG compliance, Team360 assessment pagination, and message attachment preview behavior. It also adds new documentation for a recent fix and updates changelogs and feature documentation for clarity and accuracy.

Accessibility Documentation Improvements:

• Added checklist items and retest instructions to ensure the accessWidget trigger does not obscure chat controls at any viewport size, and clarified the files involved in fixing focus-obscured issues (global.scss, styles.scss, index.html). [1] [2] [3]

Assessment Pagination and Team360 Flow Clarifications:

• Updated assessment flow and feature toggle documentation to clarify Team360 pagination: each configured group now renders on its own page, selector-free groups can appear anywhere, and navigation skips unused placeholder pages. Submission requirements and completion logic for Team360 are now described in more detail, including the distinction between peer and non-peer groups and stricter submission guards. [1] [2] [3] [4] [5] [6]

• Documented new UI logic for assessment/review submit buttons, including a distinct loading state, proper ARIA attributes, and clear separation between validation and loading disables.

• Clarified display logic for reviewer-only multiple/oneof questions, ensuring all choices are shown with clear statuses in both feedback and review-complete modes. [1] [2]

Documentation and Changelog Updates:

• Added a new fix documentation page for "CORE-8316 Immediate Message Attachment Preview," describing the real-time contract for chat attachments, preview logic, and verification steps.
• Updated the main documentation changelog to include the new fix and a profile picture upload fix.
• Updated review dates in assessment flow and feature toggle documentation for accuracy. [1] [2]

Minor Styling Clarification:

• Added a comment clarifying that .label styling in the slider rating implementation uses shared sizing and typography.**

[trtshen]

Note: The failing CI check error is caused by gitleaks/gitleaks-action@v2 require a GITLEAKS_LICENSE secret for organization-owned repositories.