Add two-stage Dockerfile with CGO support

- Build stage: golang:1.24-alpine with vips-dev for CGO image libs
- Runtime stage: alpine:3.21 with vips runtime only
- Pass VERSION build arg for ldflags embedding
- Add 'make docker' target to build image with git version

Makefile

@@ -1,4 +1,4 @@
-.PHONY: check lint test fmt build clean
+.PHONY: check lint test fmt build clean docker
 
 VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
 LDFLAGS := -X main.Version=$(VERSION)
@@ -29,11 +29,15 @@ test:
 # Build the binary
 build: ./bin/pixad
 
-./bin/pixad: ./internal/*/*.go ./cmd/pixad/*.go
+./bin/pixad: ./internal/*/*.go ./cmd/pixad/*.go ./internal/static/* ./internal/templates/*
 	@echo "Building pixad..."
 	go build -ldflags "$(LDFLAGS)" -o $@ ./cmd/pixad
 
 # Clean build artifacts
 clean:
 	rm -rf bin/
-	rm -f data.db
+	rm -rf ./data
+
+# Build Docker image
+docker:
+	docker build --build-arg VERSION=$(VERSION) -t pixad:$(VERSION) -t pixad:latest .