Fix test suite compatibility with Node v24 (CJS/ESM, locutus v3, twing v6)

[alex-ahumada]

Node v24 exposed three pre-existing incompatibilities introduced by recent dependency and runtime upgrades. This PR fixes all three.

locutus 2.x → 3.x

• Import path fix: locutus v3 added a package exports field (./* → ./esm/*.js). Importing locutus/php/datetime/date.js with the .js suffix resolved to …/date.js.js, causing uncaught exceptions across the entire test suite. Fixed by using the bare path locutus/php/datetime/date.
• Named export: locutus v3 switched from a default export to a named export (export function date). Updated to import { date }.

Node v24 CJS/ESM interop

• Node ≥22.12 adds a module.exports key to the namespace object when importing a CJS module as ESM. The exports/ tests were using a hardcoded Object.keys(exports).length - N subtraction that broke when this extra key appeared. Replaced with an explicit wrapper-key filter in all three exports tests.

twing 5.x → 6.x

twing v5 calls util.isNullOrUndefined, which Node v23 removed entirely, causing all 94 Twing tests to fail.
twing v6 is a significant rewrite. Key breaking changes addressed.

Area	What changed in v6	What we did
Filter/function factories	new TwingFilter/Function removed	→ createFilter/createFunction (same arg order)
Callable signature	All callables now receive executionContext as first arg	Added _ctx first param to all 16 callables
Template from string	env.createTemplate(str) removed	→ createArrayLoader({}) + loader.setTemplate + env.loadTemplate
safe_join	Internal join(ctx, val, glue, and) — and=undefined leaks into output	Pass null explicitly as 4th arg
placeholder	Markup objects are always truthy even when empty	String(escaped) before falsy check in wrapPlaceholder
without	Twig [] is a plain JS array, not a Map	Removed Map-flattening loop; simplified to (_ctx, element, ...args)
Argument strictness	Extra args throw at runtime if not declared	Added is_variadic: true to active_theme and active_theme_path
render_var	v6 enforces acceptedArguments at compile time	Fixed missing acceptedArguments in function registration
create_attribute	Inline hashes are plain JS objects, not Maps	Promoted from test.failing — now works correctly
|keys rendering	Arrays render as 'Array' in string context (closer to PHP Twig)	Added |join(",") in Twing-specific without tests

[alex-ahumada]

My bad, the locutus imports issues were already addressed in #63, I missed that PR.