feat: push events to ephemeral volume if Loki disabled and stdout

[rohan2794]

Description

• Added support to log events to a JSON file on the pod's ephemeral volume when Loki is disabled.
• Integrated the Rust clap crate for command-line argument parsing and configuration management.
• Implemented log rotation for JSON event files to prevent unbounded file growth when Loki is not configured.

[tiagolobocastro]

Please update the title, we're also pushing to stdout?

Also there are not chores, it's feat

[Copilot]

Pull request overview

This PR extends the events-aggregator to support exporting events to a JSON file on pod-local ephemeral storage when Loki is disabled, and wires the new component into the Nix image build/release flow.

Changes:

• Added a file-based batch exporter with simple rotation and size limiting for event JSON output.
• Switched events-aggregator configuration to clap CLI parsing (NATS URL, JetStream toggle, Loki toggle, file export options).
• Updated Nix packaging and release scripts to build and publish the new events.aggregator image.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
scripts/release.sh	Adds events.aggregator to the list of released images.
nix/pkgs/images/default.nix	Introduces build-events-image and includes events images in the build set.
nix/pkgs/extensions/default.nix	Adds the events extension derivation and installer for events-aggregator.
nix/pkgs/extensions/cargo-project.nix	Includes events-aggregator in the all-in-one cargo build set.
events-aggregator/src/main.rs	Adds clap-based CLI, exporter wiring, and updates message processing to forward compact JSON to exporter.
events-aggregator/src/exporter/mod.rs	Defines exporter module exports for integration with main.rs.
events-aggregator/src/exporter/engine.rs	Implements batching, retry loop, disk write, and rotation logic.
events-aggregator/src/constant.rs	Centralizes constants for channels, timeouts, batching, and NATS settings.
events-aggregator/src/client/nats_client.rs	Refactors to use shared constants and adjusts connection/timeouts and retry logic.
events-aggregator/Cargo.toml	Updates dependencies to include clap/url/utils plus exporter dependencies.
Cargo.lock	Captures new dependency graph changes (clap/parse-size/tracing-appender/etc).

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