Add randomUUID to CryptoProvider for edge runtime compatibility (#1404)

## Summary

Fixes #1403

- Adds `randomUUID()` abstract method to `CryptoProvider` interface
- Implements in `NodeCryptoProvider` using Node's `crypto.randomUUID()`
- Implements in `SubtleCryptoProvider` using `randomBytes(16)` with UUID
v4 bit manipulation
- Updates `AuditLogs` to use `getCryptoProvider().randomUUID()` instead
of direct Node crypto import

This ensures the audit-logs idempotency key generation works across all
supported runtimes including edge environments (Convex, Cloudflare
Workers) that cannot import the Node "crypto" package.