feat(FN-1227): add mesh state and system metrics support to CentralCore

- Add SystemMetrics, PeerNode, NodeMeshState, and MeshDiscovery types and export new mesh/metrics APIs from @fusion/core
- Introduce collectSystemMetrics with CPU, memory, storage, and uptime collection (including check-disk-space integration) plus dedicated unit tests
- Bump central DB schema to v3 with nodes.systemMetrics/knownPeers and peerNodes table, including migration coverage for v2->v3 upgrades
- Extend CentralCore with node metrics updates, peer register/unregister/list operations, mesh snapshot reporting, and event emissions backed by expanded test coverage

pnpm-lock.yaml

@@ -72,6 +72,9 @@ importers:
 
   packages/core:
     dependencies:
+      check-disk-space:
+        specifier: ^3.4.0
+        version: 3.4.0
       cron-parser:
         specifier: ^5.5.0
         version: 5.5.0
@@ -2570,6 +2573,10 @@ packages:
   chardet@2.1.1:
     resolution: {integrity: sha512-PsezH1rqdV9VvyNhxxOW32/d75r01NY7TQCmOqomRo15ZSOKbpTFVsfjghxo6JloQUCGnH4k1LGu0R4yCLlWQQ==}
 
+  check-disk-space@3.4.0:
+    resolution: {integrity: sha512-drVkSqfwA+TvuEhFipiR1OC9boEGZL5RrWvVsOthdcvQNXyCCuKkEiTOTXZ7qxSf/GLwq4GvzfrQD/Wz325hgw==}
+    engines: {node: '>=16'}
+
   check-error@2.1.3:
     resolution: {integrity: sha512-PAJdDJusoxnwm1VwW07VWwUN1sl7smmC3OKggvndJFadxxDRyFJBX/ggnu/KE4kQAB7a3Dp8f/YXC1FlUprWmA==}
     engines: {node: '>= 16'}
@@ -8152,6 +8159,8 @@ snapshots:
 
   chardet@2.1.1: {}
 
+  check-disk-space@3.4.0: {}
+
   check-error@2.1.3: {}
 
   chokidar@4.0.3: