fix: support modern otplib consumers

[Jess Sullivan (Jesssullivan)]

Summary

• add an otplib compatibility layer that supports legacy v12 authenticator exports and modern v13 functional exports
• route TOTP and invitation code through the compatibility helpers
• bump @tummycrypt/tinyland-auth to 0.3.3

Validation

• pnpm typecheck
• pnpm test
• pnpm build
• pnpm check:package
• pnpm dlx @bazel/bazelisk build //:pkg //:typecheck
• pnpm dlx @bazel/bazelisk test //:typecheck //:test --test_output=errors
• v13-consumer smoke using MassageIthaca's otplib@13.3.0