fix: pass UV index config to docker build for RC dependencies

Docker builds on release branches need access to UV_EXTRA_INDEX_URL
and UV_INDEX_STRATEGY to resolve RC client dependencies from test.pypi.

Changes:
- Add UV_EXTRA_INDEX_URL and UV_INDEX_STRATEGY build args to Containerfile
- Pass these env vars as build args in integration-tests.sh
- ENV variables are now available during uv pip install in Docker builds

scripts/integration-tests.sh

@@ -271,6 +271,16 @@ if [[ "$STACK_CONFIG" == *"docker:"* && "$COLLECT_ONLY" == false ]]; then
         --build-arg "LLAMA_STACK_DIR=/workspace"
     )
 
+    # Pass UV index configuration for release branches
+    if [[ -n "${UV_EXTRA_INDEX_URL:-}" ]]; then
+        echo "Adding UV_EXTRA_INDEX_URL to docker build: $UV_EXTRA_INDEX_URL"
+        build_cmd+=(--build-arg "UV_EXTRA_INDEX_URL=$UV_EXTRA_INDEX_URL")
+    fi
+    if [[ -n "${UV_INDEX_STRATEGY:-}" ]]; then
+        echo "Adding UV_INDEX_STRATEGY to docker build: $UV_INDEX_STRATEGY"
+        build_cmd+=(--build-arg "UV_INDEX_STRATEGY=$UV_INDEX_STRATEGY")
+    fi
+
     if ! "${build_cmd[@]}"; then
         echo "❌ Failed to build Docker image"
         exit 1