Library setup (#1)

This PR contains the work done to setup the library:
* Defined products, dependencies, and targets for the `Package` file;
* Restructured the folder structure of the library and test targets to start development work;
* Created the `DocC` documentation catalog in the library target;
* Added the `CONTRIBUTORS` and `LICENSE` files;
* Added `README` file.

Reviewed-on: #1
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Makefile

@@ -0,0 +1,104 @@
+# ===----------------------------------------------------------------------===
+# 
+# This source file is part of the MarvelService open source project
+# 
+# Copyright (c) 2025 Röck+Cöde VoF. and the MarvelService project authors
+# Licensed under the EUPL 1.2 or later.
+# 
+# See LICENSE for license information
+# See CONTRIBUTORS for the list of MarvelService project authors
+# 
+# ===----------------------------------------------------------------------===
+
+# ENVIRONMENT VARIABLES
+
+environment ?= .env
+
+include $(environment)
+export $(shell sed 's/=.*//' $(environment))
+
+# LIBRARY
+
+lib-build: ## Builds the library
+	@swift build
+
+lib-release: ## Releases the library
+	@swift build -c release
+
+lib-test: ## Runs the unit tests for the library
+	@swift test \
+		--disable-xctest \
+		--enable-code-coverage \
+		--enable-swift-testing \
+		--parallel 
+
+# SWIFT PACKAGE MANAGER
+
+pkg-clean: ## Deletes built SPM artifacts of the package
+	@swift package clean
+
+pkg-reset: ## Resets the complete SPM cache/build folder of the package
+	@swift package reset
+
+pkg-pristine: pkg-clean pkg-reset ## Deletes all built artifacts, caches, and documentations of the package
+	@rm -drf $(DOCC_ARCHIVE_OUTPUT)
+	@rm -drf $(DOCC_GITHUB_OUTPUT)
+
+pkg-outdated: ## Lists the SPM package dependencies that can be updated
+	@swift package update --dry-run
+
+pkg-update: ## Updates the SPM package dependencies
+	@swift package update
+	
+# DOCUMENTATION
+
+doc-generate: doc-generate-archive doc-generate-github ## Generates the library documentation for both Github and Xcode
+
+doc-generate-archive: ## Generates the library documentation archive for Xcode
+	@swift package \
+		--allow-writing-to-directory $(DOCC_ARCHIVE_OUTPUT) \
+		generate-documentation \
+		--target $(SPM_LIBRARY_TARGET) \
+		--include-extended-types \
+		--enable-inherited-docs \
+		--output-path $(DOCC_ARCHIVE_OUTPUT)
+
+doc-generate-github: ## Generates the library documentation for Github
+	@swift package \
+		--allow-writing-to-directory $(DOCC_GITHUB_OUTPUT) \
+		generate-documentation \
+		--target $(SPM_LIBRARY_TARGET) \
+		--disable-indexing \
+		--transform-for-static-hosting \
+		--include-extended-types \
+		--enable-inherited-docs \
+		--hosting-base-path $(DOCC_GITHUB_BASE_PATH) \
+		--output-path $(DOCC_GITHUB_OUTPUT)
+
+doc-preview: ## Previews the library documentation in Safari
+	@open -a safari $(DOCC_PREVIEW_URL)
+	@swift package \
+		--disable-sandbox \
+		preview-documentation \
+		--target $(SPM_LIBRARY_TARGET) \
+		--include-extended-types \
+		--enable-inherited-docs
+
+# IDE
+
+ide-xcode: ## Opens this package with Xcode
+	@open -a Xcode Package.swift
+
+ide-vscode: ## Opens this package with Visual Studio Code
+	@code .
+
+# HELP
+
+# Output the documentation for each of the defined tasks when `help` is called.
+# Reference: https://marmelab.com/blog/2016/02/29/auto-documented-makefile.html
+.PHONY: help
+
+help: ## Prints the written documentation for all the defined tasks
+	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)
+
+.DEFAULT_GOAL := help