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/local-store/phase-memory.json

@@ -0,0 +1,3 @@
+{
+  "schema_version": "phase_memory.local_store.v1"
+}