Hub stage 3: the console in hub mode

With info.hub the node selector reads Server / All servers, the default-credentials
password prompt and the account actions the hub cannot serve are gone, the header
status reports the servers an aggregate could not reach (hubWarnings, kept until the
next aggregate), and merged Query Logs show a Server column. Without the flag
nothing changes. The hub sends hubWarnings on every aggregate answer, empty when all
servers answered, and never on a single-node one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hub/server.test.ts

@@ -209,6 +209,7 @@ describe('single node', () => {
     expect(b.calls[0].query.get('token')).toBe('token-b')
     expect(b.calls[0].query.has('node')).toBe(false)
     expect(b.calls[0].query.get('type')).toBe('LastDay')
+    expect(body.hubWarnings).toBeUndefined()
   })
 
   it('reports an unreachable server by its id', async () => {
@@ -235,7 +236,7 @@ describe('aggregate', () => {
       const { body } = await call('dashboard/stats/get', params, token)
       expect(body.response.stats.totalQueries).toBe(400)
       expect(body.response.mainChartData.datasets[0].data).toEqual([400, 400])
-      expect(body.hubWarnings).toBeUndefined()
+      expect(body.hubWarnings).toEqual([])
     }
   })