ui: F1 — populate OpenAlerts in baseView so nav badge updates everywhere

Flagged in review of cd38b40: the Alerts tab badge should show the
open count from any page, not just /alerts. baseView now takes the
request and queries store.ListAlerts(Status: "open") to fill
view.OpenAlerts on every page render. All call sites updated.

internal/server/http/ui_sources.go

@@ -121,7 +121,7 @@ func (s *Server) handleUIHostSources(w stdhttp.ResponseWriter, r *stdhttp.Reques
 	// loadHostChrome already counted groups; reuse count we just got.
 	chrome.SourceGroupCount = len(groups)
 
-	view := s.baseView(u)
+	view := s.baseView(r, u)
 	view.Title = host.Name + " sources · restic-manager"
 	view.Page = hostSourcesPage{hostChromeData: chrome, Groups: rows}
 	if err := s.deps.UI.Render(w, "host_sources", view); err != nil {
@@ -139,7 +139,7 @@ func (s *Server) handleUISourceGroupNewGet(w stdhttp.ResponseWriter, r *stdhttp.
 	if !ok {
 		return
 	}
-	view := s.baseView(u)
+	view := s.baseView(r, u)
 	view.Title = "New source group · " + host.Name + " · restic-manager"
 	view.Page = sourceGroupEditPage{
 		hostChromeData: s.loadHostChrome(r, *host, "sources", "new source group"),
@@ -173,7 +173,7 @@ func (s *Server) handleUISourceGroupEditGet(w stdhttp.ResponseWriter, r *stdhttp
 		stdhttp.Error(w, "internal", stdhttp.StatusInternalServerError)
 		return
 	}
-	view := s.baseView(u)
+	view := s.baseView(r, u)
 	view.Title = g.Name + " · " + host.Name + " · restic-manager"
 	form := formFromGroup(*g)
 	form.PreHook = s.decryptHookOrFallback(g.PreHook, "", host.ID, "pre")
@@ -362,7 +362,7 @@ func (s *Server) handleUISourceGroupDelete(w stdhttp.ResponseWriter, r *stdhttp.
 // typed input intact + an error banner. Returns 422 to signal "form
 // rejected" while still returning HTML (mirrors handleUIAddHostPost).
 func (s *Server) renderSourceFormError(w stdhttp.ResponseWriter, r *stdhttp.Request, u *ui.User, host *store.Host, gid string, isNew bool, form sourceFormData, msg string) {
-	view := s.baseView(u)
+	view := s.baseView(r, u)
 	view.Title = "Source group · " + host.Name + " · restic-manager"
 	saveAction := "/hosts/" + host.ID + "/sources/new"
 	crumb := "new source group"