Compose both of a rotating node's logins from the vault's node-logins, so its engine can test-dial the new one

ADR 0583 §1 (insight 2026-11-01) and §2: the grants part reads the vault's node-logins as its named reader and
composes a node user per login, both while the node rotates and the new one alone after rotation-done; each node's
engine reads its own node's key alone (composed by mesh-sdk while the vault serves rotate-node). The part follows the
state by watch, so a rotation begun or ended composes again at once. A second login is judged its node's when the
list is compared (Placed), and a hash changing by a rotation node-logins names is not counted as a writer changing
several hashes at once (sealed.go). The state not on the bus yet is a standing gap: every node logs in as node.<n>,
as today. Tested as a subtest of TestGrants, no new test function. Built against the group's mesh-sdk head 5000774
through a go.work outside the worktree; the pin is the lead's.

(issue 774, 774/S53)

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

modules/mesh-grants/module.json

@@ -23,7 +23,8 @@
     "mesh-vault.bus-accounts",
     "mesh-controller.lease",
     "mesh-conditions.takeover",
-    "mesh-enrolment.enrolments"
+    "mesh-enrolment.enrolments",
+    "mesh-vault.node-logins"
   ],
   "consumes": [
     "mesh-conditions.condition-raised",