feat: add a runtime diagnostics page

Adds GET /api/clouds/:cloud/diagnostics and a Diagnostics page in the
General nav. The report combines, in one call:

- runtime reachability, latency, version and edition from /_floci/health
- every service the runtime emulates, with the console pages backed by it
- per-console-service probes (the existing status check)
- EC2 instance containers from /_floci/diagnose
- console uptime, sign-in mode and active session count

Each source is optional, so a down runtime still yields a partial report.

packages/frontend/src/App.tsx

@@ -4,6 +4,7 @@ import {SecretsManagerPage} from '@/features/secretsmanager/SecretsManagerPage'
 import {CloudExplorerPage} from '@/pages/CloudExplorerPage'
 import {CloudConsoleHomePage} from '@/pages/CloudConsoleHomePage'
 import {DatabaseDataPage} from '@/pages/DatabaseDataPage'
+import {DiagnosticsPage} from '@/pages/DiagnosticsPage'
 import {DynamoDbItemEditorPage} from '@/pages/DynamoDbItemEditorPage'
 import {WorkflowStudioPage} from '@/pages/WorkflowStudioPage'
 
@@ -18,6 +19,10 @@ export default function App() {
                     <Route path="/console/azure" element={<Navigate to="/console/aws" replace/>}/>
                     <Route path="/console/gcp" element={<Navigate to="/console/aws" replace/>}/>
                     <Route path="/console/:cloud" element={<CloudConsoleHomePage/>}/>
+                    <Route path="/diagnostics" element={<Navigate to="/diagnostics/aws" replace/>}/>
+                    <Route path="/diagnostics/azure" element={<Navigate to="/diagnostics/aws" replace/>}/>
+                    <Route path="/diagnostics/gcp" element={<Navigate to="/diagnostics/aws" replace/>}/>
+                    <Route path="/diagnostics/:cloud" element={<DiagnosticsPage/>}/>
                     <Route path="/cloud-explorer" element={<Navigate to="/cloud-explorer/aws/storage" replace/>}/>
                     <Route path="/cloud-explorer/azure/*" element={<Navigate to="/cloud-explorer/aws/storage" replace/>}/>
                     <Route path="/cloud-explorer/gcp/*" element={<Navigate to="/cloud-explorer/aws/storage" replace/>}/>