Add escalation tool test documentation

[nonggde]

Closes #603

Summary

• repair the folder-local Escalation Tool README and specs placeholders
• add a contributor-facing test plan and review notes
• add synthetic escalation fixture cases covering monitor, needs-owner, manager-review, and urgent-escalation states
• add a zero-dependency Node documentation/fixture contract test

Scope

• only touches tools/v2/team/escalation-tool/
• no app shell, routing, auth, wallet, Stellar, database, inbox, mail rendering, notification, ticketing, or design-system integration
• no live network calls, secrets, production data, persistence, or side effects

Validation

• node --test tools/v2/team/escalation-tool/tests/escalation-docs.test.mjs
• npx --yes prettier --check on the changed Escalation Tool files
• git diff --check
• ASCII scan over tools/v2/team/escalation-tool