feat(#401): add public model types for ModemManager domain

mmrs/CHANGELOG.md

@@ -3,3 +3,12 @@
 All notable changes to the `mmrs` crate will be documented in this file.
 
 ## [Unreleased]
+
+### Added
+
+- Public model types for the ModemManager domain under `mmrs::models`:
+  `Modem`, `ModemState`, `AccessTechnology`, `Sim`, `SimLockState`,
+  `Bearer`, `BearerConfig`, `BearerStats`, `Ip4Config`, `IpType`,
+  `ModemError`, and the `Result` alias. All public structs and enums are
+  `#[non_exhaustive]`; `BearerConfig` ships with `with_*` builder methods.
+

mmrs/Cargo.toml

@@ -11,5 +11,6 @@ categories = ["api-bindings", "asynchronous"]
 
 [dependencies]
 log.workspace = true
+thiserror.workspace = true
 zbus.workspace = true
 zvariant.workspace = true

mmrs/src/api/mod.rs

@@ -1 +1,7 @@
+//! Public-facing API surface for the `mmrs` crate.
+//!
+//! Currently exposes the [`models`] sub-module; higher-level helpers
+//! (entry-point `ModemManager` struct, builders, etc.) will land here as
+//! the crate grows.
 
+pub mod models;