fix(kida): type toAccessor by what it actually returns

[dangreen]

toAccessor and toAccessorOrSignal decide what to do with a typeof test:

export function toAccessor(source: unknown) {
  return isAccessor(source)
    ? source
    : () => source
}

isAccessor is typeof value === 'function'. It cannot tell an accessor from a callback, and it does not try — either one is handed back untouched.

The types said otherwise. They tested AnyAccessor, which is Accessor<any> — a zero-argument function. A callback takes an argument, so it is not assignable, so it fell through to the wrapping branch:

const wrapped = toAccessor((event: Event) => String(event.type))
// typed   Accessor<(event: Event) => string>
// is      (event: Event) => string

toAccessorOrSignal was wrong the same way, and worse — it claimed a WritableSignal of the callback.

Both now test AnyFn, which is what the runtime tests:

export type ToAccessor<T> = [T] extends [AnyFn]
  ? T
  : Accessor<Exclude<T, AnyFn>> | Extract<T, AnyFn>

Nothing else changes. A plain value still becomes Accessor<T>, an accessor or a signal still comes back as itself; only the case that was already lying is corrected.

Types only — every bundle in the chain is byte-identical, and no size pin moves. Checked across all eleven packages: lint, tsc --noEmit and the unit suites are green.

This matters beyond the two functions: nanoviews' props$ reads props in accessor form with the same typeof rule, and it types its result with ToAccessor. Before this fix, a callback prop taken as $onSelect would have been typed as an accessor wrapping the callback rather than as the callback itself.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.33%. Comparing base (2891ec4) to head (d600d91).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #208   +/-   ##
=======================================
  Coverage   85.33%   85.33%           
=======================================
  Files         139      139           
  Lines        3143     3143           
  Branches      591      591           
=======================================
  Hits         2682     2682           
  Misses        332      332           
  Partials      129      129           

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