M9(3/3): SPEC.md bump to 'shipped 2026-06-15'

M9 scope complete:
- Layer 6: per-component circuit breaker (closed → half-open → open)
- Layer 7: per-source quarantine (Redis sorted-set hit counter + TTL ban)
- deliverd metrics: delivery_attempts_total, dlq_total, dlq_latency, retry_attempts
- routerd metrics: recipient_expansion_seconds histogram
- Prometheus: scrape split (deliverd-fcm + deliverd-telegram), archiverd added
- Grafana: provisioning dashboards + datasources, BroadAnnounce Overview

SPEC.md

@@ -863,7 +863,7 @@ ingestd_rejection_latency_seconds_bucket{transport,reason} histogram
 | M1 | + layers 1, 4, 5 (size cap, per-company, schema) |
 | M5 | + layer 2 (per-IP cap, obvious once WS is in) |
 | M6 | + dedupe-aware rate shaping (don't burn a token on a dupe) |
-| M9 | + layer 6 (circuit breaker), layer 7 (quarantine), all metrics + dashboards |
+| M9 | + layer 6 (circuit breaker), layer 7 (quarantine), all metrics + dashboards (shipped 2026-06-15) |
 | M10 | prove one runaway source can't push p99 above 5s for *other* sources (loadgen fault-injection) |
 
 ### What we explicitly do NOT add in v1