feat(node26): add ESNext.Intl and ESNext.Date to lib

[DASPRiD]

The Node 26 base sets lib to ["es2025", "ESNext.Collection", "ESNext.Temporal"]. ESNext.Temporal declares the Temporal namespace, but the Intl integration lives in ESNext.Intl, so formatting a Temporal value does not type check even though Node 26 supports it:

const formatter = new Intl.DateTimeFormat("de-DE", { dateStyle: "long" });
const date = Temporal.PlainDate.from("2026-08-10");

formatter.format(date);
// error TS2345: Argument of type 'PlainDate' is not assignable to
// parameter of type 'number | Date | undefined'.

Adding ESNext.Intl compiles clean.

ESNext.Intl declares two things, and Node 26 implements both. Checked against Node 26.3.1:

Temporal-aware Intl.DateTimeFormat methods (format, formatToParts, formatRange, formatRangeToParts):

> new Intl.DateTimeFormat("de-DE").format(Temporal.PlainDate.from("2026-08-10"))
'10.8.2026'
> new Intl.DateTimeFormat("de-DE").formatRange(Temporal.PlainDate.from("2026-08-10"), Temporal.PlainDate.from("2026-08-12"))
'10.–12.08.2026'

Intl Locale Info methods on Intl.Locale:

> const locale = new Intl.Locale("de-DE");
> locale.getCalendars()        // [ 'gregory' ]
> locale.getCollations()       // [ 'emoji', 'eor', 'phonebk' ]
> locale.getHourCycles()       // [ 'h23' ]
> locale.getNumberingSystems() // [ 'latn' ]
> locale.getTextInfo()         // { direction: 'ltr' }
> locale.getTimeZones()        // [ 'Europe/Berlin', 'Europe/Busingen' ]
> locale.getWeekInfo()         // { firstDay: 1, weekend: [ 6, 7 ] }

So nothing in ESNext.Intl is declared ahead of what the runtime provides.

_version bumped to 26.1.0, matching how other Node bases version revisions.

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Second commit: the same reasoning applies to ESNext.Date. The Temporal proposal adds one method to Date — Date.prototype.toTemporalInstant(), the migration bridge from legacy dates — and Node 26 ships it, but its declaration lives in ESNext.Date:

new Date().toTemporalInstant();
// error TS2339: Property 'toTemporalInstant' does not exist on type 'Date'.

With both additions, the base covers the complete Temporal lib surface (ESNext.Temporal, ESNext.Intl, ESNext.Date).