Add fleet control: service configs, replica floors, monitor, pause/restart

Central fleet.json sets min/max copies. Tree-node keepFloor respawns
until three healthy unpaused replicas remain. CLI and loopback UI
pause, resume, stop, and restart instances that fail health checks.

packages/verae-fleet/services/tree-node.json

@@ -0,0 +1,16 @@
+{
+  "id": "tree-node",
+  "title": "Merkle tree-node archive",
+  "kind": "nats-archive",
+  "package": "verae-tree-node",
+  "role": "tree-node",
+  "managed": true,
+  "runtime": "N copies holding leaf proofs for bulk summaries",
+  "health": { "type": "http", "path": "/health", "timeoutMs": 800 },
+  "ports": { "healthBase": 13600 },
+  "nats": {
+    "in": ["verae.archive.put", "verae.archive.query"],
+    "out": ["verae.archive.reply.<correlationId>"]
+  },
+  "notes": "keepFloor in fleet.json must stay >= 3 so a leaf query still has a node that might hold the shard. Bloom miss = no packet."
+}