feat: update health endpoint

[mattjohnsonpint]

• Remove agents from health endpoint (causing perf issues, and not needed)
• Add go version and kubernetes namespace to health endpoint
• Optimizations / cleanup

[Copilot]

Pull Request Overview

Refactors the health endpoint to remove agent details, introduce Go version and Kubernetes namespace fields, and centralize JSON object construction, while caching the namespace lookup for performance.

• Added a reusable MakeJsonObject utility and KeyValuePair type.
• Updated health handler to use the new JSON helper, removed agents list, and added go_version and optional kubernetes_namespace.
• Wrapped the Kubernetes namespace lookup in a sync.OnceValues cache and updated the changelog.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
runtime/utils/json.go	Introduce KeyValuePair and MakeJsonObject for manual JSON assembly
runtime/httpserver/health.go	Refactor health endpoint to use MakeJsonObject, remove agents, and add go_version & namespace
runtime/app/app.go	Cache Kubernetes namespace lookup with sync.OnceValues
runtime/actors/agents.go	Remove deprecated ListLocalAgents function
CHANGELOG.md	Added entry for the health endpoint update

Comments suppressed due to low confidence (4)

runtime/httpserver/health.go:27

• [nitpick] Changing the field key from "version" to "app_version" may break existing consumers; consider retaining the original key or clearly documenting this breaking change.

		{Key: "app_version", Value: app.VersionNumber()},

runtime/httpserver/health.go:28

• Introduce unit tests to verify the "go_version" field is present and correctly reflects the runtime.Version() output in the health endpoint response.

		{Key: "go_version", Value: runtime.Version()},

runtime/httpserver/health.go:31

• Add tests to cover the optional "kubernetes_namespace" field, ensuring it appears only when the namespace lookup succeeds.

		data = append(data, utils.KeyValuePair{Key: "kubernetes_namespace", Value: ns})

runtime/httpserver/health.go:34

• [nitpick] Pretty-printing the health JSON adds CPU overhead per request; consider using compact output in high-throughput scenarios or making pretty-printing configurable.

	_, _ = w.Write(utils.MakeJsonObject(data, true))