ui: split /hosts/{id} into host page + /runs/{runID} run page

Host page owns host metadata, full runs table with per-row stage strip,
in-flight banner, and empty-state CTA. Run page owns pipeline, active
step, logs, sub-steps, spec diffs, and hold banner with a breadcrumb
back to the host. Dashboard tile reverts to host-only.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/httpserver/router.go

@@ -70,11 +70,12 @@ func NewRouter(d Deps) http.Handler {
 	r.Get("/", d.UI.Dashboard)
 	r.Get("/hosts/new", d.UI.NewHostForm)
 	r.Post("/hosts", d.UI.CreateHost)
-	r.Get("/hosts/{id}", d.UI.HostDetail)
+	r.Get("/hosts/{id}", d.UI.HostPage)
 	r.Post("/hosts/{id}/delete", d.UI.DeleteHost)
 	r.Post("/hosts/{id}/start", d.UI.StartRun)
 	r.Post("/hosts/{id}/cancel", d.UI.CancelRun)
 	r.Post("/hosts/{id}/override-wipe", d.UI.OverrideWipeStorage)
+	r.Get("/runs/{runID}", d.UI.RunPage)
 	r.Get("/reports/{runID}", d.UI.Report)
 	r.Get("/register/quick.sh", d.UI.QuickRegisterScript)
 	r.Get("/events", d.UI.SSE)