R-1125: the install page shows the check's own memory reading

The deploy page read /proc's host-wide figures (system.GetMemoryMB) while the install check reads the guest cap and
the installed apps' committed requests; on 9202 the page said 12,637 MB needed where the check counted 2,648. Both
now read stacks.InstallMemory. TestR1125_InstallMemoryIsTheChecksReading, red-proved.

Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/handlers.go

@@ -688,9 +688,10 @@ func (s *Server) deployPageData(w http.ResponseWriter, r *http.Request, name str
 	// Memory info for deploy page (only for non-deployed apps)
 	if !alreadyDeployed {
 		memInfo := map[string]interface{}{"Available": false}
-		totalMB, usedMB, memErr := system.GetMemoryMB()
-		if memErr == nil {
-			reservedMB := s.cfg.System.ReservedMemoryMB
+		// R-1125: the SAME reading the install check judges (guest total, reserve, installed apps' requests) — never
+		// /proc's host-wide figures, which made this box and the check disagree.
+		totalMB, reservedMB, usedMB, memOK := s.stackMgr.InstallMemory()
+		if memOK {
 			usableMB := totalMB - reservedMB
 			newReqMB := stacks.ParseMemoryMB(meta.Resources.MemRequest)
 			afterMB := usedMB + newReqMB