feat(cli): add version check and update commands

- Add `trc -v` to check for new versions from RubyGems.org
- Add `trc update` command to update t-ruby to latest version
- Create VersionChecker class for API communication

Author: yhk1038

lib/t_ruby.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative "t_ruby/version"
+require_relative "t_ruby/version_checker"
 require_relative "t_ruby/config"
 
 # Core infrastructure (must be loaded first)

lib/t_ruby/cli.rb

@@ -13,7 +13,8 @@ class CLI
         trc --watch, -w          Watch input files and recompile on change
         trc --decl <file.trb>    Generate .d.trb declaration file
         trc --lsp                Start LSP server (for IDE integration)
-        trc --version, -v        Show version
+        trc update               Update t-ruby to the latest version
+        trc --version, -v        Show version (and check for updates)
         trc --help, -h           Show this help
 
       Examples:
@@ -44,6 +45,12 @@ def run
 
       if @args.include?("--version") || @args.include?("-v")
         puts "trc #{VERSION}"
+        check_for_updates
+        return
+      end
+
+      if @args.include?("update")
+        update_gem
         return
       end
 
@@ -78,6 +85,24 @@ def run
 
     private
 
+    def check_for_updates
+      result = VersionChecker.check
+      return unless result
+
+      puts ""
+      puts "New version available: #{result[:latest]} (current: #{result[:current]})"
+      puts "Run 'trc update' to update"
+    end
+
+    def update_gem
+      puts "Updating t-ruby..."
+      if VersionChecker.update
+        puts "Successfully updated t-ruby!"
+      else
+        puts "Update failed. Try: gem install t-ruby"
+      end
+    end
+
     def init_project
       config_file = "trbconfig.yml"
       src_dir = "src"

lib/t_ruby/version_checker.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require "net/http"
+require "json"
+require "uri"
+
+module TRuby
+  class VersionChecker
+    GEM_NAME = "t-ruby"
+    RUBYGEMS_API = "https://rubygems.org/api/v1/gems/#{GEM_NAME}.json".freeze
+
+    def self.check
+      new.check
+    end
+
+    def self.update
+      new.update
+    end
+
+    def check
+      latest = fetch_latest_version
+      return nil unless latest
+
+      current = Gem::Version.new(VERSION)
+      latest_version = Gem::Version.new(latest)
+
+      return nil if current >= latest_version
+
+      { current: VERSION, latest: latest }
+    end
+
+    def update
+      system("gem install #{GEM_NAME}")
+    end
+
+    private
+
+    def fetch_latest_version
+      uri = URI(RUBYGEMS_API)
+      response = Net::HTTP.get_response(uri)
+
+      return nil unless response.is_a?(Net::HTTPSuccess)
+
+      data = JSON.parse(response.body)
+      data["version"]
+    rescue StandardError
+      nil
+    end
+  end
+end