add four new appendix sections covering idea sources, double diamond model, jobs to be done, and mom test interview method. includes both zh-cn and en versions with comprehensive content and navigation updates.
update introduction.md and stage-0 index files to include new sections in tables of contents. add sidebar navigation entries in config.mjs for all languages.
each new appendix provides beginner-friendly explanations, practical frameworks, and AI integration tips for product development and validation.
sanbuphy
4512c010bd