v0.72.0

• Introduced CODE_COMMENT_CONTEXT_FILENAME environment variable for configuring custom context files
• Changed default context file path from contexts/code_comment.rb to .contexts/code_comment.rb
• Added diagnostic output to indicate which context file is being used, sent to STDERR
• Maintained backward compatibility when no environment variable is set
• Moved default context generation to a dedicated default_context variable for improved organization