Refactor: Create core:api module and set up publishing (#4362)

core/model/README.md

@@ -60,3 +60,22 @@ classDef unknown fill:#FFADAD,stroke:#000,stroke-width:2px,color:#000;
 
 </details>
 <!--endregion-->
+
+## Meshtastic Core Models
+
+This module contains the Parcelable data classes used by the Meshtastic Android app and its API. These models are designed to be shared between the service and client applications via AIDL.
+
+### Key Classes
+
+*   **`DataPacket`**: Represents a mesh packet (text, telemetry, etc.).
+*   **`MeshUser`**: Represents a user/node on the mesh.
+*   **`NodeInfo`**: Contains detailed information about a node (position, SNR, battery, etc.).
+*   **`Position`**: GPS location data.
+
+### Usage
+
+This module is typically used as a dependency of `core:api` but can be used independently if you need to work with Meshtastic data structures.
+
+```kotlin
+implementation("com.github.meshtastic.Meshtastic-Android:core-model:v2.7.12")
+```