[Feature] Add process-local in-memory KV indexer and Router integration (#33370)

Co-authored-by: Wu, Yutong <yutong.wu@amd.com>
Co-authored-by: TianDi101 <ditian12@amd.com>
Co-authored-by: Zhangheng <hzh0425@apache.org>

experimental/sgl-router/tests/e2e/k8s_integration/Dockerfile.router

@@ -10,7 +10,11 @@ FROM rust:1.90-bookworm AS builder
 # `channel = "1.90"`.
 ENV RUSTUP_TOOLCHAIN=1.90.0
 
-# libssl-dev + pkg-config ship with rust:1.90-bookworm already; no apt-get needed.
+# libssl-dev + pkg-config ship with rust:1.90-bookworm already; protoc does not,
+# and the Indexer's build script needs it to compile the KV-indexer protos.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends protobuf-compiler \
+    && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /build