[build] configure iOS signing and Xcode Cloud dependencies

apps/ios/ci_scripts/ci_post_clone.sh

@@ -0,0 +1,37 @@
+#!/bin/sh
+
+set -eu
+
+SCRIPT_DIR="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
+IOS_DIR="$(dirname "$SCRIPT_DIR")"
+REPO_DIR="$(git -C "$IOS_DIR" rev-parse --show-toplevel)"
+HOST_TOOLS_DIR="${IOS_DIR}/.xmake/xcode-cloud-host"
+
+if ! command -v brew >/dev/null 2>&1; then
+    echo "Xcode Cloud requires Homebrew to install the iOS build tools." >&2
+    exit 69
+fi
+
+echo "Installing Xcode Cloud native build tools"
+brew install xmake cmake python@3.13
+BREW_PREFIX="$(brew --prefix)"
+PYTHON_PREFIX="$(brew --prefix python@3.13)"
+
+# Match GitHub Actions' host Python dependencies without modifying Homebrew's
+# externally managed Python. The Xcode build phase selects this environment
+# explicitly because exports here do not persist into later Cloud steps.
+"${PYTHON_PREFIX}/bin/python3.13" -m venv "$HOST_TOOLS_DIR"
+"${HOST_TOOLS_DIR}/bin/python3" -m pip install --upgrade pip setuptools wheel
+for tool in xmake xrepo cmake ctest cpack; do
+    ln -sf "${BREW_PREFIX}/bin/${tool}" "${HOST_TOOLS_DIR}/bin/${tool}"
+done
+
+"${HOST_TOOLS_DIR}/bin/xmake" --version > "${HOST_TOOLS_DIR}/xmake-version.txt"
+"${HOST_TOOLS_DIR}/bin/python3" -B "${IOS_DIR}/scripts/verify_native_build.py" \
+    --xmake-version "${HOST_TOOLS_DIR}/xmake-version.txt"
+
+echo "Initializing MiniRTC submodules"
+git -C "$REPO_DIR" submodule sync --recursive
+git -C "$REPO_DIR" submodule update --init --recursive
+
+echo "Xcode Cloud iOS build tools are ready"