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.

apps/server/src/routes/setup.ts

@@ -62,11 +62,13 @@ export async function setupRoutes(
   const adminGuard = requireRole("admin");
 
   // Catalog of selectable drivers per category (no secrets — schema only).
-  // `discoverable` flags drivers that can scan the LAN.
+  // `discoverable` flags drivers that can scan the LAN; `pushCapable` flags
+  // drivers that push to the backend (and thus need a backend IP at assign time).
   app.get("/api/setup/catalog", async () => {
     const catalog = registry.catalog();
     const discoverable = registry.list().filter(isDiscoverable).map((d) => d.id);
-    return { ...catalog, discoverable };
+    const pushCapable = registry.pushCapable();
+    return { ...catalog, discoverable, pushCapable };
   });
 
   // Scan the LAN for devices a driver can discover (UDP broadcast, etc).