style(centralui): full-app bg-light/bg-white -> theme-aware utility sweep (M10 residual)

T34c only fixed the bounded modal-surface offenders. Bootstrap 5.3's bg-light
and bg-white are fixed light values that do NOT flip under [data-bs-theme=dark],
so every remaining use was a dark-mode contrast break. 35 swaps across 19 files:

  surface / <pre> / <code>  bg-light                -> bg-body-secondary
  panel                     bg-white                -> bg-body
  neutral badge             bg-light text-dark      -> bg-secondary-subtle text-secondary-emphasis
  muted badge / input group bg-light text-muted     -> bg-body-secondary text-body-secondary

DELIBERATELY LEFT (7 sites): the neutral member of a status-badge switch or
ternary whose siblings are all solid, non-theme-aware colours (bg-success,
bg-danger, bg-warning) — swapping only the neutral one to a subtle token breaks
the visual weight of the set, so these stay until the whole family is retoned:
  Topology.razor:513 (Current badge) and :588 (InstanceState.NotDeployed)
  InstanceConfigure.razor:1520 (same InstanceState switch)
  NotificationReport.razor StatusBadgeClass fallback
  TransportImport.razor ConflictKind badge fallback
  SecuredWrites.razor text-bg-light fallback (a text-bg-* family with no
    theme-aware member at all)
  Health.razor:377 depth ternary
Also untouched by design: SchemaBuilder.razor:88 (already bg-light-subtle,
theme-aware), bg-dark text-light console panels, and site.css / #reconnect-modal.

InstanceConfigure.razor is edited concurrently elsewhere; its change here is 5
pure class-string swaps on existing lines, no reflow. No test asserted any of
these classes. Also marks all four M10 residuals done in the plan doc.

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Shared/AlarmTriggerEditor.razor

@@ -9,7 +9,7 @@
      RangeViolation   { attributeName, min, max }
      RateOfChange     { attributeName, thresholdPerSecond, windowSeconds, direction } *@
 
-<div class="border rounded bg-white p-3">
+<div class="border rounded bg-body p-3">
 
     @* ── Monitored attribute ───────────────────────────────────────────── *@
     @* Expression triggers reference attributes inside the C# expression itself,
@@ -54,7 +54,7 @@
             </select>
             @if (_selectedDataType is { } dt)
             {
-                <span class="input-group-text bg-light text-muted small">@dt</span>
+                <span class="input-group-text bg-body-secondary text-body-secondary small">@dt</span>
             }
         </div>