Add cspell to CI

[yamcodes]

Add cspell to GitHub Actions to catch spelling errors across all files. Configure with cspell.json in the repo root.

[HoudaBelhad]

Hi @yamcodes,
I’d like to implement the cspell integration for CI. Could you clarify:

• Are there specific files or directories you want to include or exclude from spell checking?

• Are there any project-specific words (like class names, acronyms, library names) that should be added to the dictionary to avoid false positives?

[yamcodes]

Hey @HoudaBelhad!

Include (files worth spell-checking):

• src/**/*.java - solution and test code
• *.md - README, CONTRIBUTING, CLAUDE.md
• pom.xml - project config

Exclude (not worth checking):

• .idea/** - IDE config
• the specific leetcode slugs we use (like minimumdeletionstomakestringbalanced for example), we can probably achieve it with this regex: "codes\\.yam\\.leetcode\\.[a-z]+"
• anything else in .gitignore (probaby cspell default behavior)

For the words to ignore, anything flagged as a typo and is not actually a typo should be ignored.

This includes: "Borodetsky", "markdownlint", "Belhad", "leetcode", "yam", "javadoc"