feat(agera,intl,kida,nanoviews,query,router,svelte-kit): rename ValueOrAccessor to Signalish

[dangreen]

interface ButtonProps {
  title: ValueOrAccessor<string>
  size?: ValueOrAccessor<'s' | 'm' | 'l'>
  onSelect: (event: Event) => void
  id?: string
}

ValueOrAccessor is the type a consumer of this library writes most: 705 occurrences in this repo, 577 of them in dom/attributes.ts alone. It is fifteen characters of noun-conjunction-noun, and no other library spells it that way.

interface ButtonProps {
  title: Signalish<string>
  size?: Signalish<'s' | 'm' | 'l'>
  onSelect: (event: Event) => void
  id?: string
}

Where the name comes from

Only three ecosystems publish a "plain value or reactive thing" union at all, and all three name it as a modifier on a noun rather than a conjunction:

	name	where it is used
Preact	Signalish<T> = T | SignalLike<T> (preact/src/dom.d.ts)	1088 times in jsx.d.ts — the DOM attribute types, the same position as ours
solid-primitives	MaybeAccessor<T> = T | Accessor<T>	headless primitives
Vue	MaybeRef<T>, MaybeRefOrGetter<T>	composable signatures

Angular, Svelte, nanostores, MobX, RxJS, Jotai, Zustand and Recoil ship no such union — their props are either plain or always wrapped.

Signalish is the shortest of the three, and it comes from the library whose usage matches ours exactly. The union is written over Accessor, but ReadableSignal<T> extends Accessor<T>, so from the writing side there is no difference to see: a signal, an accessor, or a plain value all fit, and a signal is what gets passed most.

What else moves with it

• MaybeAccessorValue → SignalishValue, so the extractor keeps the name of the union it extracts from. (Preact pairs Signalish with UnpackSignal; a noun reads better here than a verb.)
• AnyValueOrAccessor → AnySignalish.
• query's SignalsParams → SignalishParams — it maps every element of a parameter tuple through this union, so it promised signals while accepting plain values too.
• Parameters that spelled the old name — valueOrAccessor, valueOrReadable — are now source.

Nothing breaks

Every old name stays as a deprecated alias, marked for removal:

/**
 * @deprecated Use `Signalish`
 * @todo Drop at the next major
 */
export type ValueOrAccessor<T> = Signalish<T>

ValueOrSignal and ValueOrWritableSignal are aliased too. They have no consumer left in this repo and were on the way out, but dropping a published export is the break this PR is avoiding.

Types cost nothing at runtime: every bundle in the chain is byte-identical and no size pin moves.

Checked

All eleven packages: lint, tsc --noEmit, and unit suites — agera 155, kida 64, store 57, nanoviews 114, query 163, router 129, intl 114, preact 9, react 15, svelte 4, svelte-kit 21.

The narrowing types TruthyValueOrSignal/FalsyValueOrSignal in nanoviews belong to the same family and follow in a separate PR; they are left untouched here so this one stays mechanical.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.33%. Comparing base (47f794b) to head (7507eb4).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #210   +/-   ##
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  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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