Add mail-to-ticket converter architecture contract

[nonggde]

Closes #619

Summary

• repair the Mail-to-Ticket Converter README/specs placeholders for the V2 team tool
• add a folder-local architecture contract covering components, services, hooks, tests, and docs
• document ticket draft data ownership, dependency rules, prohibited production ownership, and future adapter constraints
• add a zero-dependency Node documentation contract test for the architecture boundary

Scope

• only touches tools/v2/team/mail-to-ticket-converter/
• no app shell, dashboard, routing, auth, wallet, Stellar, database, inbox, mail rendering, ticket creation/update, notification, webhook, external ticketing provider, 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/architecture-contract.test.mjs
• npx --yes prettier --check on the changed Mail-to-Ticket Converter files
• git diff --check
• ASCII scan over tools/v2/team/mail-to-ticket-converter