Stop master-key peers from outliving their devices

A deleted master key could keep letting its devices in: ui.db learns what
is on a server only from awg-ctrl's reply, and a node that executed a
request whose 504/502 reply got lost, or a device deleted while a
reconcile pass was in flight, left a peer nothing remembered to remove.

- awg-ctrl: PUT /api/peers/sync takes a panel's full list of wanted keys
  and removes every other peer of that panel's area. Removal is driven
  only by such an explicit list, never by time or inactivity: a panel
  that is offline sends nothing, so nothing is deleted. Registered before
  PUT /api/peers/:pub, with its own 512 kB body limit.
- Every panel has a stable id (ui.db, mirrored to awg-ui/panel.id) and
  adds peers as "<panel>/m<key>/d<device>", so two panels on one awg-ctrl
  never touch each other's peers. Legacy "m1/d2" peers are claimed only
  when their key is in the panel's list.
- Each reconcile pass ends with the sync, built from ui.db at that moment.
  Its reply also self-heals: a device whose key is missing on a server
  (a rekey rolled back after a lost reply) is added again.
- Deleting a master key stops it at once but keeps it listed as
  "Удаляется — ждёт: …" until every server confirms, instead of saying
  "deleted" while an offline node still lets the devices in.
- Deleting a node reconciles it first; if it is offline or has not
  confirmed a deleted key, it takes ?force=1 and a warning. Tombstones
  are no longer dropped silently.
- /sub/v1: an unknown device gets a signed 410 revoked that does not count
  towards the failure limit (dead clients behind one node NAT used to
  lock everyone out), every response echoes the request's ts and device,
  and 401 reasons and the first 429 per window are logged. config and rev
  are unchanged, byte-identical on one server.
- CLI: `awg-ctrl peers [drop <area|legacy>]` lists and removes
  subscription peers by area; `join --no-panel` asks whether to keep or
  drop the panel's own peers (NODE_PEERS=keep|drop).

awg-ui/src/App.tsx

@@ -102,7 +102,15 @@ export default function App() {
     const deleteNode = useCallback(async (n: NodeInfo) => {
         if (!confirm(`Удалить сервер «${n.name}»? Нода отключится от панели.`)) return;
         try {
-            await apiFetch('DELETE', `/ui/nodes/${n.id}`, token);
+            try {
+                await apiFetch('DELETE', `/ui/nodes/${n.id}`, token);
+            } catch (e) {
+                // Сервер не подтвердил, что снял пиров удалённых мастер-ключей (не в сети) —
+                // панель объясняет, что останется, и удаляет только с согласия.
+                const data = axios.isAxiosError(e) ? e.response?.data : undefined;
+                if (!data?.can_force || !confirm(`${data.error}\n\nВсё равно удалить «${n.name}»?`)) throw e;
+                await apiFetch('DELETE', `/ui/nodes/${n.id}?force=1`, token);
+            }
             showMsg('Сервер удалён');
             await loadNodes(token);
         } catch (e) {