feat(ui): reload the SPA on maintenance recovery

The deploy that ends a maintenance window may ship a client-incompatible change
(wire/schema bump), and the in-session bundle is the old one. On recovery, reload to
pick up the fresh client instead of just hiding the overlay. Ordering is safe: the edge
maintenance flag (deploy/prod-deploy.sh) spans the WHOLE roll and clears only at script
exit — after the gateway (which serves the embedded SPA) has rolled — so the edge 503s
everything until the entire deploy is live; recovery therefore always serves the new SPA.
A window.__maint.recover() hook + e2e cover the reload.

ui/src/lib/maintenance.svelte.ts

@@ -41,7 +41,8 @@ export function reportMaintenance(retryAfterMs: number): void {
   if (probe) schedulePoll();
 }
 
-/** clearMaintenance lowers the overlay and stops the poll (a successful read, or reset). */
+/** clearMaintenance lowers the overlay and stops the poll without reloading (a reset, or the
+ *  e2e hook). Prod recovery goes through maintenanceRecovered instead. */
 export function clearMaintenance(): void {
   active = false;
   if (pollTimer) {
@@ -50,6 +51,21 @@ export function clearMaintenance(): void {
   }
 }
 
+/** maintenanceRecovered runs when the edge answers again after a window we were showing.
+ *  The deploy that ended the window may have shipped a client-incompatible change (a wire /
+ *  schema bump), and the running bundle is the OLD one — so reload to pick up the fresh
+ *  client instead of merely hiding the overlay. A no-op unless the overlay was up; the cover
+ *  stays over the brief reload flash. In prod recovery is the only way the overlay clears. */
+export function maintenanceRecovered(): void {
+  if (!active) return;
+  active = false;
+  if (pollTimer) {
+    clearTimeout(pollTimer);
+    pollTimer = null;
+  }
+  if (typeof location !== 'undefined') location.reload();
+}
+
 /** retryNow forces an immediate re-check (the overlay's button). It never closes the
  *  overlay itself — only a successful probe does. A no-op while a probe is in flight. */
 export function retryNow(): void {
@@ -73,7 +89,7 @@ function runProbe(): void {
   probe().then(
     () => {
       probing = false;
-      clearMaintenance();
+      maintenanceRecovered();
     },
     () => {
       probing = false;