Real Hikvision/Dahua camera driver; gate Backend-push-IP on capability

Replace the camera stub with HttpCamera: Hikvision ISAPI and Dahua CGI
snapshots over client-side HTTP Digest (new drivers/http-digest.ts).
healthCheck() now pulls a real frame instead of returning ready/stub.
Snapshot carries bytes (driver fetches); storage/imageRef is the caller's
job, keeping the adapter free of storage deps.

Fix the cosmetic Backend-push-IP field: add pushesToBackend to DeviceDriver
(only Dingtian sets it), expose as pushCapable in the catalog, and gate the
wizard's backend-IP fetch + field on it so pull-only devices hide it.

Verified on hardware (Hikvision 10.0.10.121): healthCheck ready,
captureSnapshot returns a valid JPEG.

packages/devices/src/drivers/access-dingtian.ts

@@ -721,6 +721,7 @@ export const dingtianDriver: AccessDriver = {
   description:
     "Dingtian network relay+input board (UDP). Inputs are decoupled from relays — enables host-in-the-loop entry. Unauthenticated UDP: isolate the VLAN.",
   transports: ["udp"],
+  pushesToBackend: true, // HTTP-pushes input/button events to the backend (Input Link URL)
   configFields: [
     hostField,
     { ...portField(60001), required: false, help: "Dingtian string protocol UDP port — status read (default 60001)." },