Webhooks beta and team roles

#Added

• Webhooks (beta). Relay can now push events (deploy finished, route errored, quota warning) to endpoints you register. Deliveries retry three times. Beta caveat: payload signing lands before GA.
• Team roles. Invite teammates as admin, deployer, or viewer. Viewers get read-only access to logs and metrics, which is what most stakeholders actually want.
• relay whoami shows the active account, team, and key scope.

#Fixed

• Log timestamps are now consistently UTC in both the CLI and dashboard. Apologies to everyone who debugged an incident with mixed timezones.
• Secrets containing $ no longer need double escaping.