feat: support local BGP in Expo config plugin

[artus9033]

Summary

Support local BGP in Expo config plugin with new option useLocalGradlePlugin, available both in the config file & Expo config plugin options.

Test plan

CI green.

[Copilot]

Pull request overview

This PR extends the @callstack/react-native-brownfield Expo config plugin to support loading the Brownfield Gradle plugin locally (via includeBuild) and introduces a unified configuration flow where the Expo plugin can resolve options from brownfield.config.* / package.json#brownfield as well as legacy app.json plugin props.

Changes:

• Add useLocalGradlePlugin option and wire it through Expo Android prebuild Gradle modifications (settings.gradle includeBuild + skipping Maven classpath injection).
• Introduce a shared “Expo plugin config resolution” module in @callstack/brownfield-cli and update the Expo plugin to consume it (plus overlap protection between file config and plugin props).
• Update CLI config loading semantics (loadBrownfieldConfig can return null), schema/types/docs, and migrate an example app config to brownfield.config.json.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/react-native-brownfield/src/expo-config-plugin/withBrownfield.ts	Switch Expo plugin config resolution to shared CLI resolver + overlap guard.
packages/react-native-brownfield/src/expo-config-plugin/types/android/BrownfieldPluginAndroidConfig.ts	Add useLocalGradlePlugin option to Android plugin config type.
packages/react-native-brownfield/src/expo-config-plugin/android/withBrownfieldAndroid.ts	Pass useLocalGradlePlugin into Gradle modification helpers.
packages/react-native-brownfield/src/expo-config-plugin/android/utils/gradleHelpers.ts	Implement includeBuild insertion + skip Maven classpath when local plugin enabled.
packages/react-native-brownfield/src/expo-config-plugin/android/utils/tests/gradleHelpers.test.ts	Add unit tests covering the new Gradle helper behavior.
packages/react-native-brownfield/src/expo-config-plugin/android/tests/withAndroidModuleFiles.test.ts	Extend fixture config with useLocalGradlePlugin.
packages/cli/src/types.ts	Add Expo-only nested config types (android.expo, ios.expo) incl. useLocalGradlePlugin.
packages/cli/src/expoPluginConfig.ts	New shared resolver/overlap-check module for Expo config plugin consumption.
packages/cli/src/config.ts	Make loadBrownfieldConfig return `BrownfieldConfig
packages/cli/src/brownie/config.ts	Handle loadBrownfieldConfig() possibly returning null.
packages/cli/src/brownie/tests/config.test.ts	Adjust tests for config loading behavior changes.
packages/cli/src/brownfield/utils/project.ts	Refine Expo project detection and error behavior when app config exists but Expo config parsing fails.
packages/cli/src/brownfield/commands/publishAndroid.ts	Run Expo prebuild earlier and adjust project root handling.
packages/cli/src/brownfield/commands/packageIos.ts	Run Expo prebuild earlier and adjust project root handling.
packages/cli/src/brownfield/commands/packageAndroid.ts	Run Expo prebuild earlier and adjust project root handling.
packages/cli/src/brownfield/commands/tests/packageIos.action.test.ts	Update mocks and assertions for adjusted package:ios command flow.
packages/cli/src/tests/expoPluginConfig.test.ts	Add tests for overlap detection + resolver mapping across config sources.
packages/cli/src/tests/config.test.ts	Update tests for loadBrownfieldConfig returning null when no source exists.
packages/cli/schema.json	Add android.expo / ios.expo schema definitions incl. useLocalGradlePlugin.
packages/cli/package.json	Export new ./expo-plugin-config entrypoint.
docs/docs/docs/getting-started/ios.mdx	Rename referenced config file to brownfield.config.json.
docs/docs/docs/getting-started/expo.mdx	Document preference for config file, overlap warning, and useLocalGradlePlugin.
docs/docs/docs/getting-started/android.mdx	Rename referenced config file to brownfield.config.json.
docs/docs/docs/api-reference/configuration.mdx	Document Expo project config sharing and android.expo.* / ios.expo.* layout.
apps/ExpoApp55/package.json	Remove inline brownfield config block from package.json.
apps/ExpoApp55/brownfield.config.json	Add dedicated Brownfield config file for the example Expo app.
apps/ExpoApp55/app.json	Register plugin without options (config comes from file).
apps/ExpoApp54/app.json	Register plugin without options.
.changeset/vast-waves-itch.md	Changeset for local BGP support in Expo plugin.
.changeset/nine-mice-fall.md	Changeset for unified config file support in Expo.

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