fix(rust): protocol 13 — a configuration save that settles after its reload (F9, D179)

The plugin now answers a save once the files are written, with pending and
a writeId, and reports the reload later as a config.outcome event. The save
is recorded as reloading with a settle_by of two plugin ceilings plus slack
on the database's clock; ingest settles the row by (server, writeId), only
while it is still reloading, so a replay moves nothing and a late outcome
still lands. A row past settle_by reads as lost.

GET /admin/rust/config/:serverId/writes/:writeId serves the poll; the page
polls it every two seconds, holds the Save button while it waits, and says
whether a rolled-back plugin came back on its old file. config.outcome is
a staff kind: it carries the server's log tail.

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

client/src/api.js

@@ -220,6 +220,12 @@ export const adminConfig = {
 
   writes: (serverId, limit = null) =>
     req(`/admin/rust/config/${encodeURIComponent(serverId)}/writes${query({ limit })}`),
+
+  // One write, polled while its reload settles (protocol 13). A save that
+  // reloads a plugin answers before the reload has finished — behind a cold
+  // compile that can be many seconds — and this is where the outcome lands.
+  write: (serverId, id) =>
+    req(`/admin/rust/config/${encodeURIComponent(serverId)}/writes/${encodeURIComponent(id)}`),
 }
 
 // ── the admin.users.detail extension slot ─────────────────────────────────