module: consider ObservableInput return types for Module.configure/postConfigure

## Context

`packages/modules/module/src/types.ts` defines the `Module` interface. Its `configure` and `postConfigure` members currently return `TConfig | Promise` and `void | Promise` respectively.

## Task

- Consider changing the return types of `configure`/`postConfigure` to `ObservableInput` / `ObservableInput` (or similar) for consistency with the rest of the framework's observable-based APIs.
- Add a reference/link to `IConfigurationBuilder` in the `configure` member's TSDoc, once such a type exists or is identified.

## Note

Filed while resolving `no-todo-without-issue` fusion-lint warnings on pre-existing `// @todo` comments above `Module.configure` and `Module.postConfigure`.

Start in packages/modules/module/src/types.ts and read the Module interface, especially the configure and postConfigure members and their existing TSDoc. Compare those signatures with the framework’s observable-based APIs, identify IConfigurationBuilder if available, and consider the return-type and documentation changes; done means the intended types and reference are agreed and reflected there.

Written by the indexing model from the issue text.