Add audit logging for gateway configuration changes #3112

Description

Add an audit log to the gateway that records all configuration changes — API deployments, undeployments, policy updates, and other mutations — along with the actor, timestamp, and operation details. This enables operators to audit what changed, when, and by whom.

Changes that should be captured include:

• API deploy / undeploy / update via the gateway-controller REST API
• Policy attachment or detachment
• Gateway configuration changes (auth config, TLS, uptime changes)

The audit log should be queryable (e.g. via a REST endpoint on gateway-controller) and persistent (survives restarts).

Version

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Related Issue

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