feat(PMEM-WP-0017): federated store management CLI and activity reports

Add phase_memory.management for cross-store discovery and windowed
activity reporting. Extend the phase-memory CLI with stores list and
report commands, plus make report-7d for the default weekly operator view.

tests/fixtures/management/ops-warden-store/metadata.json

@@ -0,0 +1,5 @@
+{
+  "created_at": "2026-07-01T10:00:00+00:00",
+  "profile_id": "ops-warden-coordination",
+  "schema_version": "phase_memory.ops_warden.runtime.v1"
+}