Generates Java stubs from proto/driverpb/driver.proto via the
protobuf plugin (sourceSets points at the shared root proto dir).
Pulls in dev.mobile:maestro-client:1.40.0, grpc-netty-shaded,
slf4j-simple, and the JUnit vintage engine so the gRPC test rules
work alongside JUnit Jupiter.
Kotlin 2.1.21 (deviation from plan's 1.9, forced by Gradle 9
compatibility), JDK 17 toolchain, application plugin with main
entry dev.uatu.sidecar.MainKt. Shadow 9.0.0-rc2 for the fat JAR.
Actual gRPC server wires in with task #10.
pj