Skip Bundler source-control tasks in CI to fix release workflow

The rubygems/release-gem action runs `rake release`, which tries to
create and push a git tag. This fails because the bump job already
created the tag. Clear the guard_clean and source_control_push tasks
in CI so `rake release` only builds and pushes the gem.

https://claude.ai/code/session_01CvCNpdSjh1STBdmS9n5DN9

Author: claude

Rakefile

@@ -1,6 +1,16 @@
 # frozen_string_literal: true
 
 require "bundler/gem_tasks"
+
+# In CI the release workflow already handles tags via the bump job,
+# so skip Bundler's source-control tasks to avoid "tag already exists" errors.
+if ENV["CI"]
+  Rake::Task["release:guard_clean"].clear
+  task "release:guard_clean"
+  Rake::Task["release:source_control_push"].clear
+  task "release:source_control_push"
+end
+
 require "rake/testtask"
 
 Rake::TestTask.new(:test) do |t|