feat: add EscalationTool ui component with accessible states

[AbuJulaybeeb]

What was done

• Created a folder-local React component (EscalationTool.tsx) for the primary tool workflow.
• Implemented state management to handle and display idle, loading, empty, error, and success states with mocked active escalation data.
• Integrated comprehensive accessibility considerations including role="region", aria-live="polite" for state updates, aria-busy, proper tabIndex focus behavior, and semantic HTML structure.
• Maintained isolated visual styling using generic Tailwind utility classes without mutating the shared design system.
• Exported the component via index.ts.

Why it was done

This establishes the local user interface surface for the Escalation Tool, ensuring that the tool is accessible and functional as an isolated piece of work (V2 later-release). It prepares the feature for future data integration while maintaining strict boundaries from the main application shell and existing routing.

How it was verified

• Verified that all changes are strictly localized inside src/tools/v2/team/escalation-tool/.
• Confirmed that the UI is completely isolated and is not mounted in the main application.
• Verified keyboard navigability and ARIA attribute validity for screen readers across all simulated component states.

closes #601