Backups to master, replacement-VPS restore, broker proxy, multi-instance

Four features:

- Backup: lib/backup-sync.ts pushes the full settings table and firm
  credentials (the deliberate exception to "credentials never leave the
  machine") to the master's bearer-gated /api/instances/backup — every
  5 minutes when the content hash changed, within seconds of a settings
  or credential edit, and on the new backup-now command. Enabled by the
  master_backup_token setting.

- Restore: a dead VPS's replacement pulls the backup and adopts its
  uuid/name, so roster, payouts and card links carry on. Pre-boot via
  seed-settings.js --restore-from (setup-linux.sh prompts for it) or
  the Settings page's restore picker (lib/backup-restore.ts). Stop the
  old machine first; the master 409s a live-name rename.

- Proxy: the proxy_url setting routes BROKER traffic only — TopstepX
  REST + SignalR hub, Tradovate REST + websocket, Yahoo quotes — via
  lib/outbound-proxy.ts (axios agents, undici dispatcher, ws agent).
  The master link, reporter, catalog and backup push stay direct, so a
  dead proxy cannot take down the control channel. Restart to apply.

- Multi-instance: AUTOFIRMER_DB moves the SQLite file so one checkout
  runs N instances; scripts/instances.json (per-device, gitignored)
  drives start-all/update-check, and add-instance.sh / remove-instance.sh
  manage the extra PM2 processes. Absent registry = single-instance
  behavior, unchanged. Instance 1 keeps port 3000 for the clicker and
  extension.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/api/firms/[id]/credentials/route.ts

@@ -2,12 +2,15 @@ import { NextRequest, NextResponse } from 'next/server';
 import { getCachedFirm } from '@/lib/firm-catalog';
 import { setCredentials, clearCredentials } from '@/lib/db';
 import { reconcileClients, removeClient } from '@/lib/clients';
+import { scheduleBackupPush } from '@/lib/backup-sync';
 
 type Params = { params: Promise<{ id: string }> };
 
 /** The platform login for one firm. This is the only firm data this machine
- *  owns — everything else comes from the master catalog, and these credentials
- *  never go the other way.
+ *  owns — everything else comes from the master catalog. The one path these
+ *  credentials travel is the encrypted, bearer-gated backup to the master
+ *  (lib/backup-sync.ts); they are still absent from the catalog and the
+ *  control socket.
  *
  *  Tradovate firms need username + password. TopstepX firms need the API key;
  *  username is optional for now (the loginKey call still wants it, so the
@@ -36,6 +39,7 @@ export async function PUT(req: NextRequest, { params }: Params) {
         setCredentials(id, firm.name, username, password, apiKey);
         // Picks up the new login immediately rather than at the next restart.
         reconcileClients();
+        scheduleBackupPush();
         return NextResponse.json({ ok: true });
     } catch (err) {
         console.error('[PUT /api/firms/:id/credentials]', err);
@@ -47,5 +51,6 @@ export async function DELETE(_req: NextRequest, { params }: Params) {
     const { id } = await params;
     const cleared = clearCredentials(id);
     removeClient(id);
+    scheduleBackupPush();
     return NextResponse.json({ ok: cleared });
 }