Add CLAUDE.md file

[jongfeel]

These task is create online meetup record document for every weekend.

1. Reference GitHub repository: https://github.com/ThinkAboutSoftware/OnlineSelfCodingGroup
2. Analysis README.md and Stamps/README.md files
3. Use given GitHub issue link

README.md task

1. Update joined count given issue link to current year and quater.
2. Add next given issue link date (next weekend) to current year and quater.
3. Get joined assignees list from given issue link.
4. Reference issue title given issue link include date string then update +1 count for each assignees to two ranking table - current year ranking table and all ranking table

Stamp/README.md task

1. Add stamp iamge, starbuks image, book count from given issue link.
2. Rules1: additional starbucks image for every 4 stamp image
3. Rules2: add +1 book count not stamp count but participate count