v0.13.1: UI polish fixes round 2 (4 fixes)

- Fix 1: deploy-cross-drive card uses correct CSS vars (--bg-secondary, --border-color)
- Fix 2: Auto-generated env values — badge inline with label, remove copy buttons, muted readonly inputs
- Fix 3: Snapshot table shows 0 instead of n/a; remove unused .col-na CSS
- Fix 4: Disk warnings moved inline under storage bars (Inline alert field, GetInlineAlerts, inline-warning CSS)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

controller/internal/web/templates/layout.html

@@ -31,7 +31,7 @@
 {{if .Alerts}}
 <div class="alerts-container">
     {{range .Alerts}}
-    {{if or (not .PageOnly) (pageMatch .PageOnly $.Page)}}
+    {{if and (not .Inline) (or (not .PageOnly) (pageMatch .PageOnly $.Page))}}
     <div class="alert-banner alert-banner-{{.Level}}">
         <span class="alert-icon">{{if eq .Level "error"}}🔴{{else if eq .Level "warning"}}🟡{{else}}ℹ️{{end}}</span>
         <span class="alert-message">{{.Message}}</span>