Fix weak token generation vulnerability in device pairing

[kolega-dev-github-app]

Summary

This PR fixes a security vulnerability in the newToken() function that generates weak authentication tokens for device pairing. The fix addresses the root cause by using cryptographically secure random data instead of a UUID with hyphens removed.

Changes

• Use crypto.randomBytes() to generate 32 bytes (256 bits) of cryptographically secure random data
• Encode the random data as base64url for a secure, URL-safe token
• Remove the previous implementation that used a UUID with hyphens removed, which reduced entropy and made the tokens more predictable

Testing

The fix can be tested by verifying that the generated tokens are sufficiently random and unpredictable.