chore: remove obsolete docker-build/docker-push Makefile targets

The new Dockerfile expects pre-built arch-specific binaries
(bin/initium-${TARGETARCH}), so plain `docker build` without
--platform no longer works. Use `make docker-multiarch` instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mikkeldamsgaard

Makefile

@@ -29,9 +29,5 @@ docker-multiarch: cross-build
 		-t $(IMAGE):$(VERSION) -t $(IMAGE):latest --push .
 	docker buildx build --platform linux/amd64,linux/arm64 \
 		-f Dockerfile.jyq -t $(IMAGE)-jyq:$(VERSION) -t $(IMAGE)-jyq:latest --push .
-docker-build:
-	docker build -t ghcr.io/kitstream/initium:$(VERSION) .
-docker-push:
-	docker push ghcr.io/kitstream/initium:$(VERSION)
 verify-image:
 	cosign verify --certificate-oidc-issuer https://token.actions.githubusercontent.com --certificate-identity '$(COSIGN_IDENTITY)' $(IMAGE):$(VERSION)

README.md

@@ -311,9 +311,8 @@ make test
 # Option 1: Use the pre-built image
 kubectl apply -f examples/nginx-waitfor/deployment.yaml
 
-# Option 2: Build and push your own image
-make docker-build VERSION=dev
-make docker-push VERSION=dev
+# Option 2: Cross-build and push multi-arch images
+make docker-multiarch VERSION=dev
 
 # Option 3: Use the Helm chart
 helm install my-app charts/initium \