Spring boot harness worker, metric meter registry flexibility, deprecate built-in webserver

[chrishagglund-ship-it]

Pull Request type

• [ x ] Feature
• [ x ] Refactoring (no functional changes, no api changes)

---

Summary of Changes

Summary

Metrics are now published into a Micrometer MeterRegistry and exposed by the
embedding application, rather than by an SDK-owned web server.

• Spring Boot: zero-config auto-wiring. New auto-configuration in
  conductor-client-metrics binds a MetricsCollector to the application's
  MeterRegistry, and the client auto-configs auto-attach it to the client.
  SDK metrics show up on /actuator/prometheus with no wiring code.
• Plain Java: bring your own registry. New
  PrometheusMetricsCollector(MeterRegistry) constructor plus
  getMeterRegistry(); expose registry.scrape() from an endpoint you own.
• Harness converted from plain Java to a Spring Boot app, exposing metrics
  via Actuator (/metrics, /metrics-json, /health) instead of the SDK's
  embedded server — demonstrating the recommended setup.
• Deprecated (but retained) the SDK's embedded metrics server — the no-arg
  PrometheusMetricsCollector() and startServer() still work for backward
  compatibility.

Compatibility

• No breaking changes. Existing users upgrade with no code changes.
• getRegistry() keeps its original PrometheusMeterRegistry return type and
  is now deprecated in favor of getMeterRegistry() (returns the
  MeterRegistry interface, works for any registry type).
• Unrelated: ci.yml gains checks: write / pull-requests: write
  permissions for test reporting.

Release: minor (5.1.0 → 5.2.0) — additive features plus deprecations,
no breaking changes; not a bugfix.

[codecov]

Codecov Report

❌ Patch coverage is 68.42105% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...metrics/prometheus/PrometheusMetricsCollector.java	58.33%	3 Missing and 2 partials ⚠️
.../spring/OrkesConductorClientAutoConfiguration.java	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ	Complexity Δ
.../prometheus/ConductorMetricsAutoConfiguration.java	100.00% <100.00%> (ø)	2.00 <2.00> (?)
...metrics/prometheus/PrometheusApiClientMetrics.java	91.66% <100.00%> (ø)	9.00 <1.00> (ø)
...lient/spring/ConductorClientAutoConfiguration.java	94.28% <100.00%> (+0.16%)	10.00 <0.00> (ø)
.../spring/OrkesConductorClientAutoConfiguration.java	84.00% <100.00%> (+0.66%)	13.00 <0.00> (ø)
...lient/spring/ConductorClientAutoConfiguration.java	71.79% <100.00%> (+0.74%)	10.00 <0.00> (ø)
.../spring/OrkesConductorClientAutoConfiguration.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...metrics/prometheus/PrometheusMetricsCollector.java	86.09% <58.33%> (-0.72%)	39.00 <2.00> (+3.00)	⬇️

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[chrishagglund-ship-it]

doesn't seem to have any impact on performance. highlighted blip was the rollout, it's been humming along since.

[v1r3n]

these are way too many changes for something on metrics

[chrishagglund-ship-it]

this is the "sdk's shouldn't provide web server capability just for metrics - user app should implement webserver itself" concept which converts the harness worker to a spring boot app that can provide a /metrics endpoint for prometheus to scrape instead of using the sdk-provided web server capability that we want to deprecate. Also adds the "bring your own registry" capability with some extra wiring options.