publishToMavenLocal doesn't publish gradle-plugin

While setting up my environment to contribute, I found that following the README.md contributing section didn't fully prepare the project for use with my local Maven repository.

After cloning it and then running `./gradlew publishToMavenLocal` I realized one project hadn't been run: the `gradle-plugin` one, and so my example project's using the local repository and version would always fail to find the gradle plugin.

Inspecting my local Maven repo proved the point:

```
ls -1 ~/.m2/repository/org/jetbrains/compose/storytale

compiler-plugin
gallery
gallery-android
gallery-iosarm64
gallery-iossimulatorarm64
gallery-iosx64
gallery-js
gallery-jvm
gallery-wasm-js
runtime-api
runtime-api-android
runtime-api-iosarm64
runtime-api-iossimulatorarm64
runtime-api-iosx64
runtime-api-js
runtime-api-jvm
runtime-api-wasm-js
storytale-dokka-plugin
```

The way the build scripts work and having the `gradle-plugin` on a composite build, makes it necessary to also run `./gradlew :gradle-plugin:publishToMavenLocal` after setting its version to the same as the one in `gradle.properties`'s `storytale.deploy.version` property. Then the missing folders in the local repository appear and makes it possible to use it from `mavenLocal` repository.

```
ls -1 ~/.m2/repository/org/jetbrains/compose/storytale

compiler-plugin
gallery
gallery-android
gallery-iosarm64
gallery-iossimulatorarm64
gallery-iosx64
gallery-js
gallery-jvm
gallery-wasm-js
gradle-plugin
org.jetbrains.compose.storytale.gradle.plugin
runtime-api
runtime-api-android
runtime-api-iosarm64
runtime-api-iossimulatorarm64
runtime-api-iosx64
runtime-api-js
runtime-api-jvm
runtime-api-wasm-js
storytale-dokka-plugin
```

Start with the README.md contributing instructions, gradle.properties, and the gradle-plugin composite build. Run ./gradlew publishToMavenLocal and compare the local Maven repository contents with a separate :gradle-plugin:publishToMavenLocal run; done means the normal publishing workflow also makes the gradle-plugin available from mavenLocal.

Written by the indexing model from the issue text.