Add build configuration system and paper image

- Add 'make paper' target to build a Paper image with plugins based on JRE
- Introduce dynamic .env and plugins.json configuration using Makefile
- Enable users to extend builds by managing their own directories in scratch/
- Implement copy_build_files macro for reproducible build management
- Add BUILDKIT_PROGRESS and DOCKER_BUILDKIT as configurable make vars

Makefile

@@ -1,16 +1,24 @@
-DOCKER_COMPOSE_BUILD = docker compose -f docker-compose.build.yml build
+DOCKER_BUILDKIT ?= 1
+BUILDKIT_PROGRESS ?= auto
+BUILD ?= basic
+
+DOCKER_COMPOSE_OPTS = BUILDX_GIT_LABELS=full \
+	DOCKER_BUILDKIT=$(DOCKER_BUILDKIT) \
+	BUILDKIT_PROGRESS=$(BUILDKIT_PROGRESS)
+DOCKER_COMPOSE_BUILD = $(DOCKER_COMPOSE_OPTS) docker compose -f docker-compose.build.yml build
 DOCKER_COMPOSE_UP = docker compose up -d
 
 PRUNE_IMAGES = \
 	localhost/minecraft:latest \
+	localhost/minecraft:latest-paper \
 	localhost/minecraft:latest-spigot \
 	localhost/minecraft:latest-craftbukkit \
 	localhost/minecraft-jre:latest \
 	localhost/minecraft-jdk:latest
 
-.PHONY: all clean craftbukkit default install jdk jre spigot vanilla
+.PHONY: all clean configure craftbukkit default install jdk jre spigot vanilla
 default: vanilla
-all: vanilla spigot craftbukkit
+all: vanilla paper spigot craftbukkit
 
 jre:
 	$(DOCKER_COMPOSE_BUILD) minecraft-jre
@@ -21,6 +29,9 @@ jdk:
 vanilla: jre
 	$(DOCKER_COMPOSE_BUILD) minecraft-vanilla
 
+paper: jre
+	$(DOCKER_COMPOSE_BUILD) minecraft-paper
+
 spigot: jre jdk
 	$(DOCKER_COMPOSE_BUILD) minecraft-spigot
 
@@ -30,6 +41,54 @@ craftbukkit: jre jdk
 install:
 	$(DOCKER_COMPOSE_UP)
 
+# Macro to copy files if they don't already exist or are the same
+define copy_build_files
+	set -eu; \
+	BUILD=$(1) && \
+	FILE=$(2) && \
+	DIRECTORY=$(if $(3),$(3),builds) && \
+	SRC_FILE="./$${DIRECTORY}/$${BUILD}/$${FILE}" && \
+	DEST_FILE="./$${FILE}" && \
+	TEMP_DEST_FILE="$$(mktemp)" && \
+	if [ -f "$${SRC_FILE}" ]; then \
+		if [ -f "$${DEST_FILE}" ]; then \
+			cp "$${DEST_FILE}" "$${TEMP_DEST_FILE}"; \
+			if [ "$${FILE}" = ".env" ] && grep -q 'EULA=false' "$${SRC_FILE}"; then \
+				sed -i 's/EULA=true/EULA=false/' "$${TEMP_DEST_FILE}"; \
+			fi; \
+			if cmp -s "$${SRC_FILE}" "$${TEMP_DEST_FILE}"; then \
+				echo "INFO: \"$${DEST_FILE}\" is up to date."; \
+				rm "$${TEMP_DEST_FILE}"; \
+			else \
+				echo "ERROR: \"$${DEST_FILE}\" is different from \"$${SRC_FILE}\""; \
+				diff -u "$${DEST_FILE}" "$${SRC_FILE}"; \
+				rm "$${TEMP_DEST_FILE}"; \
+				exit 1; \
+			fi; \
+		else \
+			cp "$${SRC_FILE}" "$${DEST_FILE}"; \
+			echo "INFO: \"$${SRC_FILE}\" copied to \"$${DEST_FILE}\""; \
+		fi; \
+	else \
+		echo "ERROR: Source file \"$${SRC_FILE}\" does not exist."; \
+		exit 1; \
+	fi
+endef
+
+configure:
+	@if [ -d "./builds/$(BUILD)" ]; then \
+		echo "INFO: Configuring build $(BUILD) (./builds/$(BUILD))" && \
+		$(call copy_build_files,$(BUILD),.env); \
+		$(call copy_build_files,$(BUILD),plugins.json); \
+	elif [ -d "./scratch/$(BUILD)" ]; then \
+		echo "INFO: Configuring build $(BUILD) (./scratch/$(BUILD))" && \
+		$(call copy_build_files,$(BUILD),.env,scratch); \
+		$(call copy_build_files,$(BUILD),plugins.json,scratch); \
+	else \
+		echo "ERROR: Build directory for \"$(BUILD)\" not found"; \
+		exit 1; \
+	fi
+
 clean:
 	docker image rm $(PRUNE_IMAGES) || true
 	docker builder prune -f