hub v0.155.0: the floor can never deliver a withdrawn controller build (R-1085); RomM/Ghost evidence

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

hub/internal/web/templates/configuration.html

@@ -56,6 +56,9 @@
         {{if eq .Flash "floor_invalid"}}
         <div class="flash flash-error">Invalid version — use X.Y.Z (or blank to clear).</div>
         {{end}}
+        {{if eq .Flash "floor_spoiled"}}
+        <div class="flash flash-error">This version is withdrawn (a faulty build) and cannot be set as the minimum. Nothing was saved.</div>
+        {{end}}
         {{if eq .Flash "floor_needs_min_agent"}}
         <div class="flash flash-error">This floor is above the vouched golden — declare its MinAgent (from the release's CHANGELOG header). Nothing was saved.</div>
         {{end}}
@@ -125,6 +128,7 @@
             <p style="margin: 0 0 0.75rem; font-size: 0.85em;">
                 Effective floor:
                 {{if .FloorRes.Effective}}<code>v{{.FloorRes.Effective}}</code>{{else}}<span class="text-muted">none</span>{{end}}
+                {{if .FloorWithdrawn}}<span data-floor-withdrawn="1" style="color: #ef4444;">— this version is withdrawn ({{.FloorWithdrawn}}): every box is served no floor; set another version</span>{{end}}
                 {{if eq .FloorRes.Source "db"}}
                 <span style="color: #cbd5e1;">— source: <strong>DB (hub_settings)</strong>{{if .FloorRes.EnvValue}}; env fallback would be <code>v{{.FloorRes.EnvValue}}</code>{{end}}</span>
                 {{else if eq .FloorRes.Source "env"}}