Convert clients/js and clients/js-legacy to oxlint and oxfmt

[clankmaxxing-clod]

Replaces ESLint + Prettier with oxlint and oxfmt for both JS client packages (clients/js and clients/js-legacy), mirroring solana-program/token-group#115 and the follow-ups in token-metadata, libraries, memo, and record.

Changes (applied identically to clients/js and clients/js-legacy)

• package.json: dropped eslint, prettier, @typescript-eslint/eslint-plugin, eslint-config-prettier, eslint-plugin-prettier, and @solana/prettier-config-solana; added oxlint and oxfmt. Scripts now run the Oxc tools:
  • lint → oxlint --max-warnings 0
  • lint:fix → oxlint --fix
  • format → oxfmt --check .
  • format:fix → oxfmt --write .
• .oxlintrc.json (new) mirrors the old .eslintrc.cjs (@typescript-eslint/recommended): correctness category as errors, with ban-ts-comment / no-explicit-any / explicit-function-return-type / explicit-module-boundary-types disabled to match the previous rules.
• .oxfmtrc.json (new) migrated from .prettierrc.cjs via oxfmt --migrate=prettier (single quotes, trailingComma: all, printWidth 100, endOfLine: lf, semicolons).
• Removed .eslintrc.cjs, .eslintignore, and .prettierrc.cjs.
• Updated the root pnpm-lock.yaml.

Notes

• CI invokes pnpm lint / pnpm format per package through the repo Makefile, so no workflow files needed changing.
• Existing source in both packages is already oxfmt-clean and oxlint-clean — no source reformatting in this PR.

Verification

For both packages: pnpm install, pnpm lint, pnpm format, and pnpm build all succeed; clients/js pnpm test (tsc) passes. A root pnpm install --frozen-lockfile succeeds against the updated lockfile. (The clients/js-legacy ava/litesvm suite needs the on-chain program .so built via cargo build-sbf — not run in this environment; it is unaffected by the tooling change.)

🤖 Generated with Claude Code

[joncinque]

Audit failure was fixed with #776, landing on red