build: switch to oxfmt and oxlint

[TheGreatAxios]

Closes CL-9407

Summary

• Remove Prettier and ESLint (prettier, eslint, @eslint/js, typescript-eslint, jiti) with .prettierrc.json, .prettierignore and eslint.config.ts
• Add oxfmt 0.70.0 and oxlint 1.85.0 as exact-pinned devDependencies; check already calls lint and format:check
• No lint fixes needed
• .oxfmtrc.json sets printWidth: 80; everything else is oxfmt's defaults, including sorting package.json keys
• .oxlintrc.json turns the correctness category from warn to error; no rules are disabled
• lint runs oxlint, format runs oxfmt, format:check runs oxfmt --check

Commits

1. build: switch to oxfmt and oxlint: tooling and configs
2. style: format with oxfmt: mechanical reformat only (package.json key order), safe to skip in review

Checks

bun run check passes.