update readme

README.md

@@ -179,6 +179,32 @@ mvn -Pnative package jib:build -DskipTests
 mvn -Pnative jib:build -Djib.to.auth.username=admin -Djib.to.auth.password=""
 ```
 
+### Backend build (buildah)
+
+**JVM image** (`Dockerfile` — Eclipse Temurin 21):
+
+```bash
+buildah build \
+  --platform linux/arm64 \
+  --tag zot.immich-ad.ovh/ai-teacher-backend:latest \
+  backend/
+
+buildah login zot.immich-ad.ovh
+buildah push --tls-verify=false zot.immich-ad.ovh/ai-teacher-backend:latest
+```
+
+**Native image** (`Dockerfile.native` — GraalVM 25, produces a minimal Debian-slim image):
+
+```bash
+buildah build \
+  --platform linux/arm64 \
+  --file backend/Dockerfile.native \
+  --tag zot.immich-ad.ovh/ai-teacher-backend-native:latest \
+  backend/
+
+buildah push --tls-verify=false zot.immich-ad.ovh/ai-teacher-backend-native:latest
+```
+
 ### Frontend build
 ```
 buildah build \