[clue]

This changeset adds support for factory functions returning a Closure for container variables. The factory function is still invoked only once and every consumer receives the same Closure, just like with any other container variable:

$container = new FrameworkX\Container([
    'greeter' => function () {
        return function (string $name) {
            return 'Hello ' . $name . '!';
        };
    },
    Acme\Todo\UserController::class => function (\Closure $greeter) {
        return new Acme\Todo\UserController($greeter);
    }
]);

A Closure in the container configuration is always treated as a factory function, so returning one from a factory function is the only way to provide it as a value. Until now, this was not supported because the cached result would be invoked as a factory again on the next access, which #302 turned into an explicit TypeError. The cache now wraps it in a new Closure instead. Factory functions for class names are unchanged and must still return an object.

This includes a new test case covering repeated access to the same Closure. This has 100% code coverage and should be safe to apply.

Builds on top of #302, #178, #307, #288 and others

[Copilot]

🟢 Approval recommended

No active review issues block the addition of closure-valued container-variable support.

No open issues 🎉

What changed in this PR

Adds support for container-variable factories that return a Closure, preserving the returned instance across consumers while invoking the original factory only once. Class-name factory requirements remain unchanged.

Changes:

• Wraps cached closure values so later accesses do not invoke them as factories.
• Adds a regression test for shared closure identity and a single factory invocation.
• Updates the expected error when getEnv() receives a closure instead of string|null.

File	Description
tests/​ContainerTest.php	Tests closure caching and updates the getEnv() type-error expectation.
src/​Container.php	Allows closure-valued variables by wrapping cached closures.

_{Review effort: Balanced}