Adds one high-level walker per client (.NET/Python/Rust/Go/Java) plus
six unit tests each against existing fake transports. One-shot idempotent
Expand semantics; pagination hidden inside the helper. Includes Java
toolchain bootstrap (Homebrew Temurin + Gradle) so the Java client can
build locally on the macOS dev host.
OPC UA-style level-at-a-time browse across gRPC, dashboard, and the
shared cache projector. Server still loads the full Galaxy hierarchy;
laziness is wire-side and UI-side only.
Joseph Doherty