feat(rust): Admin → Rust servers page and the next wipe on the web (phase 16)

The module had no page for its own server rows: they were written only
through PUT /admin/rust/servers/:id, and the README described an
"Admin → Rust" server form that did not exist. D133 (org lead) builds it:
add, edit, test and delete a server, with the D130 wipe schedule in the
same form. The token stays write-only and an edit sends the stored
protocol back rather than re-stamping the row.

The next wipe shows on the server list and in the server page's header,
in the reader's own clock, marked "rescheduled" for a one-off date.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

client/src/lib/format.js

@@ -125,6 +125,29 @@ export function shortId(steamId) {
   return id.length > 10 ? `…${id.slice(-6)}` : id
 }
 
+/**
+ * The next wipe (phase 16, D130), as `Thu, Oct 1, 7:00 PM (in 6 days)` in the
+ * VIEWER's locale and clock — or `null` when the server has no schedule.
+ *
+ * The server computes the instant from the operator's rule in the operator's
+ * zone; the page only says it the reader's way. A `once` source is an operator
+ * moving a wipe, and says so, because "the wipe is not when it usually is" is
+ * the thing a regular needs to notice.
+ */
+export function nextWipe(value, now = Date.now()) {
+  if (!value || !value.at) return null
+  const at = toMillis(value.at)
+  if (at === null) return null
+  const when = new Date(at).toLocaleString(undefined, {
+    weekday: 'short',
+    month: 'short',
+    day: 'numeric',
+    hour: 'numeric',
+    minute: '2-digit',
+  })
+  return `${when} (${ago(at, now)})${value.source === 'once' ? ' — rescheduled' : ''}`
+}
+
 function toMillis(value) {
   if (value === null || value === undefined || value === '') return null
   if (typeof value === 'number') return Number.isFinite(value) ? value : null
@@ -133,4 +156,4 @@ function toMillis(value) {
   return Number.isNaN(parsed) ? null : parsed
 }
 
-export default { ago, clock, day, duration, count, prefab, shortId }
+export default { ago, clock, day, duration, count, prefab, shortId, nextWipe }