GDK API Foundation

**What problem would this solve?**
Goose's unrolled agent loop, as well as compaction logic are currently available only in the GRC (Goose Reference Client). We need to add them to the Rust/Kotlin/Python GDK APIs so calling programs can use them.

**What would a good outcome look like?**
* The Rust, Kotlin, Python GDK APIs will have
* Providers (done)
* Unrolled agent loop
* Compaction (PR: https://github.com/aaif-goose/goose/pull/11042)
* An API reference will be documented (TBD if per-language or some more general representation)

**Possible approaches**
* Adding the code is straightforward, we just need to decide on a `bindings.rs` interface for things
* Generating docs for rust will be cargo doc + whatever docusarus integration is needed in goose's doc site https://goose-docs.ai/

**Additional context**
N/A

- [x] I have verified this does not duplicate an existing feature request

Do not begin implementation until the issue reaches **Ready** on the [Goose Issues board](https://github.com/orgs/aaif-goose/projects/1).

Related to https://github.com/aaif-goose/goose/discussions/9848