Add Makefile for easier development workflow

Co-authored-by: BaseMax <2658040+BaseMax@users.noreply.github.com>

Author: Copilot

Makefile

@@ -0,0 +1,40 @@
+.PHONY: build test install clean run help
+
+# Binary name
+BINARY_NAME=go-config-diff
+
+# Build the binary
+build:
+	@echo "Building $(BINARY_NAME)..."
+	@go build -o $(BINARY_NAME) ./cmd/go-config-diff
+
+# Run tests
+test:
+	@echo "Running tests..."
+	@go test ./... -v
+
+# Install the binary
+install:
+	@echo "Installing $(BINARY_NAME)..."
+	@go install ./cmd/go-config-diff
+
+# Clean build artifacts
+clean:
+	@echo "Cleaning..."
+	@rm -f $(BINARY_NAME)
+	@go clean
+
+# Run the application with example
+run: build
+	@echo "Running example..."
+	@./$(BINARY_NAME) examples/config1.yaml examples/config2.yaml || true
+
+# Show help
+help:
+	@echo "Available targets:"
+	@echo "  build   - Build the binary"
+	@echo "  test    - Run tests"
+	@echo "  install - Install the binary to GOPATH/bin"
+	@echo "  clean   - Clean build artifacts"
+	@echo "  run     - Build and run with example files"
+	@echo "  help    - Show this help message"