ruby binding 追加

- FFI gem (libptouch)、exe ptouch-print-png（PNG のみ）
- ステータス 32 バイトを Hash に展開（parse_status / status_hash）
- CMake: libptouch 共有ライブラリ（ptouch_shared）
- RuboCop、gemspec（homepage / source_code_uri）

Made-with: Cursor

ruby/libptouch.gemspec

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+lib = File.expand_path("lib", __dir__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require "libptouch/version"
+
+Gem::Specification.new do |spec|
+  spec.name = "libptouch"
+  spec.version = Libptouch::VERSION
+  spec.authors = ["knb"]
+  spec.email = ["knb@artif.org"]
+
+  spec.summary = "FFI bindings for libptouch (Brother P-touch USB raster printing)"
+  spec.description = [
+    "Ruby wrapper around the ptouch_label C library libptouch.",
+    "Requires libptouch shared library (libusb, libpng)."
+  ].join(" ")
+  spec.license = "MIT"
+  spec.required_ruby_version = ">= 3.0"
+  repo = "https://gitea.artif.org/knb/ptouch_label"
+  spec.homepage = repo
+  spec.metadata["source_code_uri"] = repo
+  spec.metadata["rubygems_mfa_required"] = "true"
+
+  spec.files = Dir.chdir(__dir__) { Dir["lib/**/*.rb", "exe/*", "README.md"] }
+  spec.bindir = "exe"
+  spec.executables = ["ptouch-print-png"]
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "ffi", "~> 1.15"
+end