Add mail-to-ticket accessible UI surface

[nonggde]

Closes #621

Summary

• add a folder-local Mail-to-Ticket Converter UI surface with loading, error, empty, and success states
• add queue/detail review controls using native buttons, labels, live regions, selected-state semantics, and visible focus rings
• add synthetic UI ticket draft fixtures plus accessibility and visual style docs
• add a zero-dependency Node contract test for state coverage, ARIA/focus requirements, actions, and docs

Scope

• only touches tools/v2/team/mail-to-ticket-converter/
• no app shell, dashboard, routing, auth, wallet, Stellar, database, inbox, mail rendering, notification, ticket provider, assignment write, external service, or design-system integration
• no production data, live network calls, persistence, secrets, or side effects

Validation

• node --test tools/v2/team/mail-to-ticket-converter/tests/ui-accessibility-contract.test.mjs
• npx --yes prettier --check on the changed Mail-to-Ticket Converter UI files
• git diff --check
• ASCII scan over tools/v2/team/mail-to-ticket-converter

Note

A focused TypeScript check could not be completed in this worktree because dependencies are not installed locally, so the temporary compiler could not resolve react/lucide-react from node_modules. The repo already declares those dependencies in package.json.