feat(vision): configurability — SetupWizard ANPR toggle, footer health chip, env docs

Make the vision service genuinely configurable (was env-only).

- SetupWizard: an "ANPR" checkbox on the camera form (writes config.anpr; persisted
  only when on; sq+en) — opt-in is no longer raw JSON.
- DeviceMonitor optionally takes the VisionClient and probes /health each tick, emitting
  a "vision" pseudo-device → a Vision chip (ready/degraded/offline + recognizer) in the
  booth footer when VISION_ENABLED, no chip when off. Widened the DeviceStatus category
  union (server + web) + footer maps + devices.catVision. Verified: ready/fast_alpr when
  up, 0 chips when disabled.
- apps/vision/.env.example (Python service) + a VISION_* block in apps/server/.env.example
  (Node side) + a Configuration section in opencv-anpr-service.md covering all four
  layers and the caveats: the two processes share the VISION_ prefix but need SEPARATE
  .env files; bind /analyze to 127.0.0.1; cache model weights at deploy; an unbound anpr
  camera recognizes but every read is refused.

Build + lint green.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/SetupWizard.tsx

@@ -322,6 +322,10 @@ function DeviceForm({
   const canDiscover = !editing && selected != null && discoverableIds.includes(selected.id);
   const pushesToBackend = selected != null && pushCapableIds.includes(selected.id);
   const isController = category === "access";
+  const isCamera = category === "camera";
+  // ANPR opt-in for a camera: when true, the VisionReader polls this camera for plates
+  // (config.anpr). Off by default. See wiki/entities/opencv-anpr-service.md.
+  const [anpr, setAnpr] = useState<boolean>(editCfg?.anpr === true);
 
   // Pre-fill scalar config fields from the existing assignment when editing.
   // (relays/controllerId/relay are model fields handled by their own state below.)
@@ -429,6 +433,8 @@ function DeviceForm({
       out.controllerId = controllerId;
       out.relay = boundRelay;
     }
+    // Camera ANPR opt-in (only persisted when on, to keep configs minimal).
+    if (isCamera && anpr) out.anpr = true;
     return out;
   }
 
@@ -584,6 +590,22 @@ function DeviceForm({
             />
           )}
 
+          {/* CAMERA: opt this camera into ANPR (the VisionReader polls it for plates). */}
+          {isCamera && (
+            <label className="my-2 flex items-start gap-2 rounded-term border border-term-border bg-term-bg p-2 text-[12px]">
+              <input
+                type="checkbox"
+                className="mt-0.5"
+                checked={anpr}
+                onChange={(e) => setAnpr(e.target.checked)}
+              />
+              <span>
+                <span className="font-semibold text-term-text">{t("setup.anpr")}</span>
+                <span className="hint mt-0.5 block">{t("setup.anprHint")}</span>
+              </span>
+            </label>
+          )}
+
           {/* Test (no save/no device change) then Save (configures + persists). */}
           <div className="mt-3 flex items-center gap-2">
             <button type="button" className="btn btn-sm" onClick={test} disabled={testing}>