feat(pivot): port stdoutexporter off internal pipeline+consumer

[trilamsr]

Summary

Port components/exporters/stdoutexporter off internal/{pipeline,consumer} onto upstream OTel collector v1.59.0 / v0.153.0 types. Mirrors PR-B2 #201 (nccl_fr receiver port), exporter-flavor. Sibling self-telemetry from PR #186 stays in place — only the pipeline.ID → component.ID + pipeline.CreateSettings → exporter.Settings type-swaps in tests are needed.

Type swap

Before (internal)	After (upstream)
internal/pipeline.ExporterFactory	exporter.Factory
internal/pipeline.CreateSettings	exporter.Settings
internal/pipeline.Config	component.Config
internal/pipeline.Exporter	exporter.Metrics
internal/consumer.{Metrics,Capabilities}	consumer.{Metrics,Capabilities}
pipeline.ComponentState (embedded)	explicit no-op Start/Shutdown
pipeline.ErrSignalNotSupported (manual returns)	upstream's built-in unregistered-signal sentinel
*slog.Logger	*zap.Logger (factory-side only — exporter has no log sites)

Factory shape matches upstream-contrib (debugexporter, fileexporter):

func NewFactory() exporter.Factory {
    return exporter.NewFactory(
        componentType(),
        createDefaultConfig,
        exporter.WithMetrics(createMetrics, stability),
    )
}

WithMetrics is the only signal registered. Logs + traces fall through to upstream's built-in "telemetry type is not supported" sentinel — tests pin the surfaced message so a future upstream rename surfaces here at test-time rather than as a silent contract regression.

Root cause

RFC-0013 §migration mandates that internal/pipeline, internal/consumer, and internal/selftelemetry are deleted in PR-F. Every in-tree component must first switch to upstream OTel types so PR-F can land cleanly. PR-B2 #201 did this for the nccl_fr receiver; this PR is the exporter sibling. Not a workaround — this is the migration step itself.

Why drop pipeline.ComponentState

stdoutexporter is purely synchronous (no goroutines, no resources to acquire). The embedded ComponentState only existed to provide free Start/Shutdown/Started/Stopped accessors. Upstream component.Component requires Start/Shutdown (now explicit no-ops) but does NOT require Started/Stopped — those tests are dropped. The lifecycle helper that nccl_fr's port introduced is intentionally absent here: the exporter has no run-loop to bookend.

New adversarial tests added with the swap

• TestFactory_CreateMetrics_BadConfigType — pins the type-guard in createMetrics so a non-*Config cfg surfaces a clear error rather than panicking on type assertion.
• TestExporter_StartShutdown_NoOps — pins the no-op contract so a future refactor that introduces a side-effecting Start/Shutdown is forced to add its own test.
• TestExporter_WriteErrorSurfaces — pins the I/O failure path: a writer that errors must surface a wrapped error from ConsumeMetrics (paired with the existing kindIO selftel coverage).
• var _ exporter.Factory = NewFactory() — compile-time pin against silent regression back to internal/pipeline.ExporterFactory.

LOC delta

components/exporters/stdoutexporter/  6 files, +221 / -142
go.mod                                +6 / -0
go.sum                                +40 / -2

Net +79 LOC for the exporter package, almost entirely the four new adversarial tests above and the type-swap boilerplate the upstream contract requires (separate componentType + createDefaultConfig + createMetrics funcs vs. one struct with three methods).

Test plan

• make check — clean (fmt, tidy, lint, vet, mod-verify all green).
• go test -race -count=1 ./components/exporters/stdoutexporter/... — green.
• go test ./... — green except three pre-existing flakes (verified by stashing this diff and re-running on origin/main):
  • components/receivers/kernelevents/TestReceiver_SLIBudget (p99 perf budget; flakes ~50% on local Darwin)
  • components/receivers/kernelevents/TestKernelevents_Lifecycle_ConcurrentAddDuringShutdown_NoPanic
  • components/receivers/k8sevents/TestK8sevents_Lifecycle_ConcurrentAddDuringShutdown_NoPanic
• CI to run the same gates on a fresh checkout.

NONE