Format and lint the code with Biome, and leave the documents alone

[ken0nek]

Two commits. The first is mechanical, the second is the one worth reading.

commit	what
0464ab5	biome.json, the four scripts, and biome check --write . over 130 files. No behavior change.
db92bb1	The linter's 27 findings answered by hand, plus pnpm check:ci as a third CI job. 20 files.

0464ab5 reproduces from its own config: check out its parent, apply its
biome.json and package.json, run pnpm check, and you get its tree
byte-for-byte.

The corpus is exempt from the formatter, and only the formatter

fixtures/, recipes/, registries/ and docs/schema/ are authored by hand
in a shape no formatter produces — leaf objects on one line, key order carrying
meaning. Two of those files are read byte-for-byte by the drift checks, as is
the generated gear-labels.ts. Biome still lints all of them for JSON errors;
it just does not reprint them. Nothing under those paths changed in either
commit.

Rules that are off, and why

Repo-wide, because the compiler settings already create what they ask for:

• noNonNullAssertion — every ! in the tree exists because
  noUncheckedIndexedAccess is on. Warning on the assertions the flag creates
  is noise, not signal.
• useLiteralKeys — bracket access is what reading untyped JSON is made of.

Tests additionally waive a11y (the probe components exist to be clicked by
jsdom, not read by a person) and the two rules that the prototype-pollution and
generator-output assertions trip on purpose.

Fixed rather than waived

[^] spelled as [\s\S], forEach callbacks that returned their body's
value, void functions that returned an expression, a memo assignment hidden
inside a return, two buttons without a type, two dead imports, two hand-rolled
optional chains, six concatenations that wanted a template, and a CSS rule that
preceded the less specific selector it overrode. One suppression remains, on
JSON Schema's then keyword, which is not a thenable.

Gating now

pnpm check:ci lands in db92bb1, the commit where it first passes — the
formatting commit does not claim a gate it cannot hold. Gating at zero is the
point: a lint script that nothing runs is a cleanup someone owes later.

Verified

biome ci exit 0 · 1597 harness checks, 0 failures · 1079 tests across the
three workspaces · the site builds.