chore(ci): make quality checks non-mutating

[TheRealAgentK]

Summary

• make JavaScript and TypeScript lint scripts check-only in CI
• retain explicit eslint:fix and tseslint:fix commands for local remediation
• replace the third-party write-mode Prettier action with the repository-pinned Prettier check
• remove the Prettier job's dependency on PERSONAL_GITHUB_TOKEN

This prevents lint jobs from silently rewriting files while reporting success and makes formatting checks deterministic from package-lock.json.

Validation

• npm ci / TypeScript compilation
• npm test — 13/13 passing
• npm run eslint
• npm run tseslint
• npm exec -- prettier --check "lib/*.ts" "test/*.js" "example/*.js"

The existing dependency audit findings are deliberately unchanged and will be addressed in the next consolidated dependency/security PR.

[Olwiba]

looks good to me 👍