chore: replace Biome with oxlint, oxfmt and Knip

[Thomasims]

Moves this repository off Biome and onto the shared
@antelopejs/tooling-configs
presets, in step with the rest of the ecosystem.

Tooling swap

• @biomejs/biome and biome.json are gone.
• oxlint (pinned to 1.81.0, the version the presets' JS plugin API matches),
  oxfmt, knip, oxlint-tsgolint and eslint-plugin-perfectionist come in as
  dev dependencies.
• New oxlint.config.ts, oxfmt.config.ts and knip.config.ts, each extending
  the shared preset.
• Scripts: lint → oxlint, lint:fix → oxlint --fix, format → oxfmt .,
  plus new format:check and knip. Every other script is untouched. A
  follow-up ci: commit gates pnpm format:check and pnpm knip in
  .github/workflows/ci.yml alongside the existing pnpm lint step; there is
  no test script in this repository, so no test step was added.

The .github/ISSUE_TEMPLATE/** ignore in oxfmt.config.ts is temporary: those
files are Markdown templates with a .yml extension, which oxfmt cannot parse.
It goes away once
tooling-configs#5 ships
the shared ignore.

tsconfig

Type-aware linting runs through tsgolint, which rejects compiler options
TypeScript 7 removed and auto-discovers each file's tsconfig.json. The only
offender here was "moduleResolution": "node" (the removed node10), so the
field is dropped; tsgolint only objects to the explicit value, and the default
for module: "commonjs" is the same resolver, so the emit is unaffected.

"module": "commonjs" deliberately stays. Raising it to node16 looks like the
obvious fix and is a runtime break: tsc would stop downlevelling dynamic imports
and emit native ESM ones, bypassing the CommonJS resolver detour the ajs
runtime installs.

What the linter forced

Nothing. This repository is a single src/index.ts, and oxlint reports no
errors and no warnings on it — not even an import-order fix. Nothing was
disabled and no rule was silenced.

The one source edit is unrelated to the linter and lives in its own chore:
commit: the // biome-ignore lint/style/useConst directive above
export let connected is removed. Biome is gone, so it suppressed nothing, and
oxlint does not flag the line. AGENTS.md mandates self-documenting code without
non-TSDoc comments, so the directive is dropped outright rather than demoted to a
plain comment.

Knip

No findings, so knip.config.ts is the bare preset with no ignores at all — the
mongodb runtime dependency is genuinely imported by src/index.ts and Knip
resolves it. No exports were removed. This package is a versioned contract: its
surface is reachable only from consumers Knip cannot see, so an "unused export"
here would never be evidence of dead code.

Verification

• Public surface unchanged. dist was built from untouched origin/main
  and from this branch. The package publishes one code subpath (., plus
  ./package.json), and its runtime export keys — GetClient and internal —
  are identical. The dist tree differs from the baseline by exactly one line —
  the dead directive removed above, which main still carries and tsc copies into
  dist/index.js and its source map. Nothing else changes.
• Tests. This repository has no test suite and no test script, on
  origin/main or on this branch, so there is no baseline to compare — the
  contract is exercised by the modules that implement it.
• pnpm lint, pnpm knip and pnpm build all exit 0.

Commits

The oxfmt pass is its own commit and is recorded in .git-blame-ignore-revs, so
git blame stays readable. It only touched Markdown and package.json; no
TypeScript source was reformatted. oxfmt also normalizes package.json key
order and sorts keywords; that is expected.