fix: prepare token 1.5.1

[Priveetee]

Summary

• bind the BotGuard challenge and event identifier to the same page-native YouTube context
• preserve the matching visitor session while generating anonymous YouTube tokens
• prepare Token version 1.5.1

Production behavior

Anonymous YouTube token generation now uses the current page-native attestation context. Public Token routes and configuration remain unchanged.

Tests

• bun install --frozen-lockfile
• bun test
• bun run lint
• bun run build
• git diff --check

Rollback

Restore Token revision b49fc942.