Track creation/deletion events for server-side environment keys

### Is your feature request related to a problem?

There is no visibility of key creation/deletion events in the audit log currently.

### Describe the solution you'd like.

These events should be added to the audit log so that there is full visibility into which user, when then key was deleted and what environment this was deleted in.

### Describe alternatives you've considered

n/a

### Additional context

_No response_

Locate the server-side environment key creation and deletion handlers, then find the audit-log implementation and existing event patterns. Trace how the acting user, timestamp, and environment are recorded; done means both key lifecycle events appear in the audit log with those details and are covered by the relevant tests.

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