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.

wiki/entities/lpr-camera.md

@@ -2,7 +2,7 @@
 type: entity
 tags: [parking, hardware, readers, offline-first]
 sources: [parking-system-architecture]
-updated: 2026-06-14
+updated: 2026-06-15
 ---
 
 # LPR Camera
@@ -20,3 +20,36 @@ License-plate-recognition camera (recommended: **Milesight edge-AI LPR**). For
   host's signed [[append-only-event-chain]] entry + the controller's remote-open event) that
   should reconcile one-to-one; any mismatch is an anomaly.
 - Mounting: within ~15° of vehicle travel at a controlled chokepoint for best reads.
+
+## Snapshot driver (entry/exit fraud-control record)
+
+Separate from edge-AI LPR: the camera driver (`packages/devices/src/drivers/camera.ts`) does
+**snapshot-on-event** — the host pulls a still over HTTP when an entry/exit fires and stores it,
+referenced from the signed [[append-only-event-chain]] entry as an independent record. The camera
+**pulls, it does not push** — so it is NOT `pushesToBackend` and the setup wizard correctly hides
+the "Backend push IP" field for it (gated on the driver's `pushesToBackend` flag; only
+[[dingtian-relay]] sets it).
+
+- **Hikvision** uses **ISAPI**: `GET /ISAPI/Streaming/channels/<id>/picture` (`101` = ch1 main
+  stream) with **HTTP Digest** auth. The "Enable Hikvision-CGI" toggle (Network → Advanced →
+  Integration Protocol) is a *different* legacy CGI surface — **not** needed for ISAPI.
+- **Dahua** uses CGI: `GET /cgi-bin/snapshot.cgi?channel=<n>` (0-based channel; the wizard's
+  1-based channel is decremented).
+
+**Driver / storage boundary:** the driver FETCHES the image bytes (client-side HTTP Digest in
+`drivers/http-digest.ts`) and returns them on `Snapshot.bytes`; **storage is the caller's job**
+(the future entry/exit flow stores the bytes + mints a durable `imageRef`). This keeps the device
+adapter free of any filesystem/blob-store dependency. `healthCheck()` is honest — it actually pulls
+a frame (exercising reachability + auth + path/channel in one shot), not a fake `ready/stub`.
+
+### Verified on hardware (2026-06-15)
+
+A **Hikvision** unit ("Camera 20", MAC `94:e1:ac:…`, Hikvision OUI) at `10.0.10.121`, creds
+`admin` / `admin123` (Digest), TCP 80:
+
+- Initial `curl` test confirmed the ISAPI path returns a 2688×1520 JPEG (~306 KB).
+- The **real driver** (no longer a stub) was then run end to end against it:
+  `healthCheck()` → `ready` (pulled a frame), `captureSnapshot()` → valid `image/jpeg`, ~322 KB,
+  correct JPEG magic. Digest handshake works through `HttpCamera`.
+- Reaching it from the WSL dev box required forcing the source address (`config.localAddress`,
+  threaded into the driver) — see [[wsl-dev-networking]] (multi-subnet source-selection trap).