Update Android SDK to 6.0.0

[dtroupe-plaid]

Summary

• Port Android Expo module from stub to Plaid Android SDK 6.0.0 session APIs
• Add Android Link, Layer, Headless, result/event mapping, and Embedded Search support
• Add focused Android mapper tests and generated example Android build compatibility

Validation

• npm run lint
• npm test -- --coverage --no-watch --passWithNoTests --watchman=false
• npm run build
• cd example && npx expo prebuild --platform android --clean
• cd example/android && ./gradlew testDebugUnitTest assembleDebug

[github-actions]

Coverage after merging codex/android-sdk-6 into develop-v13 will be

100.00%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
ReactNativePlaidLinkSdkModule.ts	100%	100%	100%	100%
index.ts	100%	100%	100%	100%