feat: metrics record --emit-event for kaizen.metrics.recorded

Publish activity-core EventEnvelope payloads to NATS subject
activity.kaizen.metrics.recorded after a successful append.
Optional nats-py via kaizen-agentic[events]; project slug from
KAIZEN_PROJECT_SLUG or directory basename. Skips emit on
idempotency duplicates. Closes KAIZEN-WP-0008 T03.

src/kaizen_agentic/cli.py

@@ -15,6 +15,11 @@ from .integrations.artifact_store import (
     default_api_url,
     publish_optimizer_evidence,
 )
+from .integrations.event_bus import (
+    build_metrics_recorded_envelope,
+    publish_metrics_recorded_event,
+    resolve_project_slug,
+)
 from .integrations.helix import HelixCorrelationAdapter, enrich_helix_correlation
 from .metrics import MetricsStore, OptimizerStore, performance_summary_markdown
 from .optimization import OptimizationLoop, MIN_SAMPLES_FOR_RECOMMENDATIONS
@@ -1069,6 +1074,11 @@ def metrics():
 @click.option(
     "--json", "json_input", is_flag=True, help="Read full record JSON from stdin"
 )
+@click.option(
+    "--emit-event",
+    is_flag=True,
+    help="Publish kaizen.metrics.recorded to NATS (requires nats-py)",
+)
 def metrics_record(
     agent_name: str,
     target: str,
@@ -1079,6 +1089,7 @@ def metrics_record(
     session_id: Optional[str],
     idempotency_key: Optional[str],
     json_input: bool,
+    emit_event: bool,
 ):
     """Append one execution record for an agent."""
     store = MetricsStore(_project_root(target), agent_name)
@@ -1109,6 +1120,21 @@ def metrics_record(
 
     if store.append(payload, idempotency_key=idempotency_key):
         click.echo(f"Recorded metrics for '{agent_name}'")
+        if emit_event:
+            summary = store.read_summary() or store.write_summary()
+            envelope = build_metrics_recorded_envelope(
+                agent=agent_name,
+                project=resolve_project_slug(store.project_root),
+                summary=summary,
+            )
+            try:
+                subject = publish_metrics_recorded_event(envelope)
+            except RuntimeError as exc:
+                click.echo(f"Error: {exc}", err=True)
+                sys.exit(1)
+            click.echo(
+                f"Emitted kaizen.metrics.recorded for '{agent_name}' → {subject}"
+            )
     else:
         click.echo(
             f"Skipped duplicate record for '{agent_name}' (idempotency key exists)"