Add an open-source event ledger to self-managed NVCF

Description

Open source an event ledger suitable for self-managed NVCF and integrate it as an optional stack add-on. When enabled, NVCF services should publish lifecycle events and operators should be able to query them through public API routes. CLI convenience commands can follow the initial API integration.

Definition of Done

• The event ledger service and its deployment configuration can be built and operated from public sources without proprietary dependencies.
• The self-managed stack can enable the event ledger as an optional add-on.
• NVCF services publish lifecycle events when the add-on is enabled.
• Operators can query the recorded events through public gateway routes and APIs.