The anonymous session token is a bearer credential that was sent in the
Socket.IO handshake query string, where it leaks into proxy/access/referer
logs and is easily observed. Anyone holding it becomes that user (credits,
payout address, pending payments).
- Client now sends the token in the handshake `auth` payload instead of the
query string. Server reads `auth` first and falls back to the query string
for backward compatibility during rollout.
- The token is rotated on every successful resume, so a leaked/observed
token is invalidated the next time the legitimate owner reconnects. The
client already persists the token returned in `session_resumed`.
Adds a security test asserting resume returns a new token and the old token
no longer resumes. Full suite: 12 suites / 116 tests.