CI/CD: Spell-check documentation and code comments

[jhelison]

Is your feature request related to a problem? Please describe.
Typos and inconsistent terminology may exist in docs and comments.

Describe the solution you'd like
Add an Action that runs a spell-checker like cspell or markdownlint on docs and .go comments, failing CI on new typos.

Describe alternatives you've considered
Manual proofreading.

Additional context
Use whitelist for code terms (e.g., Tendermint, EVM, module names).

[mohitsethia]

Hi, I would like to contribute to this issue.