Dingtian relay driver — resolves the ticket-first entry blocker

The Dingtian board's inputs are independent of its relays (configurable), so a
button on an input can report to the host WITHOUT auto-firing a relay — solving
the access-controller-button-flow blocker the UHPPOTE/ZKTeco couldn't.

packages/devices:
- access-dingtian.ts: `dingtian` access driver implementing AccessControlDevice
  (relay pulse/latch via UDP string protocol :60001), InputDevice (read inputs +
  poll-based press/release events, active-LOW), and the new PreconditionDevice.
- PreconditionDevice capability on the interface: a device can report config it
  requires for parking and optionally fix it. Dingtian checks input_link_relay
  via the HTTP config API and can disable it.
- httpPort config field — the web/config API port is separate from UDP control
  (this unit uses 8080, not the default 80).
- Register dingtian; export driver objects from the package.

Verified on real hardware (DT-R004 @ 10.0.10.172): status read, relay pulse,
input events; disabled input_link_relay via the driver, then confirmed pressing
inputs fires NO relay (0000) — host-in-the-loop entry works.

Config-write gotcha recorded: config_set.cgi requires "command":"setconfig"
injected after "status" (GET omits it) or the POST silently no-ops.

apps/server/scripts/dingtian-test.mjs: status / watch / pulse hardware test.
wiki: dingtian-relay verified; button-flow marked RESOLVED; index + log.

packages/devices/src/index.ts

@@ -5,5 +5,17 @@
 
 export * from "./interfaces.js";
 export * from "./registry.js";
-export { registerBuiltinDrivers } from "./drivers/index.js";
 export { setDeviceLogSink, type DeviceLogSink } from "./drivers/common.js";
+// Built-in drivers: the registrar plus the individual driver objects (used by
+// hardware test scripts and any direct/programmatic device access).
+export {
+  registerBuiltinDrivers,
+  uhppoteDriver,
+  dingtianDriver,
+  zktecoDriver,
+  esp32RelayDriver,
+  wiegandReaderDriver,
+  tcpipReaderDriver,
+  hikvisionDriver,
+  dahuaDriver,
+} from "./drivers/index.js";