Support loading Container self-reference from Container

[clue]

This changeset adds support for loading a Container self-reference from the Container. On its own, this is rarely useful as the Container has no public API exposed at the moment. This is mostly done as an internal preparation at the moment, but may be exposed as part of our public API that allows us to reuse this logic for more classes in a follow-up.

Builds on top of #289, #284 and others

[Copilot]

Pull request overview

This PR adds support for loading a Container self-reference from the Container itself. This enables the container to inject itself into factory functions and allows Container::class to be used as a class name reference in routing and dependency injection contexts.

Key changes:

• Container can now return itself when Container::class is requested via getObject()
• Factory functions can now receive the Container as a dependency parameter
• Container::class can be used in routing configurations and will be resolved to the actual container instance

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Container.php	Implements self-reference support in loadObject() and getObject() methods, adds assertion to prevent Container in callable()
src/App.php	Updates middleware loading to support Container::class as a loadable class
src/Io/RouteHandler.php	Adds logic to resolve Container::class to container instance in route handlers
tests/ContainerTest.php	Adds comprehensive test coverage for Container self-reference scenarios including default behavior, explicit configuration, PSR-11 adapter, and recursive detection
tests/AppTest.php	Updates test expectations to account for Container::class resolution
tests/Io/RouteHandlerTest.php	Adds tests for Container::class usage in routing contexts

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

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