* fix(app): open notifications on the right host
Agent notifications previously omitted workspace ownership, so a cold target host was treated as missing and fell back to its empty home route. Carry the authoritative workspace and keep older notifications on a target-host resolver until lookup is conclusive.
* fix(app): separate notification and agent URL routing
Notifications use their authoritative workspace target directly. Stable agent URLs remain server-and-agent targets whose workspace is resolved by the agent route.
* fix(protocol): preserve notification workspace targets
Both attention message variants retain workspaceId through outbound validation so notification clicks receive the authoritative route target.
* test(app): use workspace-scoped notification target
* test(server): give notification agents workspace targets
* test(app): target notification workspace in navigation e2e
