Rongta 80mm printer: driver, role-based failover, live status monitoring

Add the rongta PrinterDevice driver (ESC/POS over raw TCP 9100) and the
device-agnostic pieces around it:

- Roles + failover: each printer declares a role (entry-dispenser/booth-
  receipt) and failoverRank; printer-routing.ts picks the best healthy printer
  and falls back outside->booth for entry tickets (never the reverse).
- Live status: MonitorableDevice.readStatus()/PrinterStatus capability. The
  Rongta driver scrapes the device's own /prn_stat.htm (Cover/Cutter/Paper
  End/Near End/Off-Line) rather than hand-decoding DLE EOT, whose reply bytes
  on this clone don't match the canonical ESC/POS bit layout (verified on
  hardware) -- avoids a false-healthy. Maps to ready/degraded/offline, fail
  safe on an unreachable or unexpected page.
- Server PrinterMonitor polls enabled printers (PRINTER_POLL_MS, default 5s),
  caches latest, emits "printer-status" on change. Exposed via
  GET /api/printers/status and an SSE stream for the booth UI.

Verified against 10.0.10.6: ready when healthy, offline when unreachable
(no throw), bus emits on change and suppresses unchanged reads.

Wiki: new rongta-printer entity, printer-roles-failover and
printer-status-monitoring concepts; BOM/index/log updated.

packages/devices/src/drivers/index.ts

@@ -4,6 +4,7 @@
 import { registry } from "../registry.js";
 import { dingtianDriver } from "./access-dingtian.js";
 import { dahuaDriver, hikvisionDriver } from "./camera.js";
+import { rongtaDriver } from "./printer-rongta.js";
 import { tcpipReaderDriver, wiegandReaderDriver } from "./reader.js";
 
 let registered = false;
@@ -17,6 +18,7 @@ export function registerBuiltinDrivers(): void {
   registry.register(tcpipReaderDriver);
   registry.register(hikvisionDriver);
   registry.register(dahuaDriver);
+  registry.register(rongtaDriver);
 }
 
 export {
@@ -25,4 +27,5 @@ export {
   tcpipReaderDriver,
   hikvisionDriver,
   dahuaDriver,
+  rongtaDriver,
 };