fix(docker): install required native build tools for Rust dependencies in the build image

Dockerfile

@@ -2,6 +2,18 @@
 ## STAGE 1 // BUILD
 FROM code.foss.global/host.today/ht-docker-node:lts AS build
 
+# System build tools that the Rust dep tree needs beyond the base image:
+#   - cmake      : used by the `cmake` crate (transitive via ort_sys / a webrtc
+#                  sub-crate) to build a C/C++ library from source when a
+#                  prebuilt-binary download path doesn't apply.
+#   - pkg-config : used by audiopus_sys and other *-sys crates to locate libs
+#                  on the native target (safe no-op if they vendor their own).
+# These are normally pre-installed on dev machines but not in ht-docker-node:lts.
+RUN apt-get update && apt-get install -y --no-install-recommends \
+      cmake \
+      pkg-config \
+ && rm -rf /var/lib/apt/lists/*
+
 # buildx sets TARGETARCH automatically for each platform it's building:
 #   linux/amd64  -> TARGETARCH=amd64
 #   linux/arm64  -> TARGETARCH=arm64