fix(ci): install client from release branch before uv sync (#4002)

Backport of #4001 to release-0.3.x branch.

Fixes CI failures on release branches where uv sync can't resolve RC
dependencies.

## The Problem

On release branches like `release-0.3.x`, pyproject.toml requires
`llama-stack-client>=0.3.1rc1`. RC versions only exist on test.pypi, not
PyPI. This causes multiple CI failures:

1. `uv sync` fails because it can't resolve RC versions from PyPI
2. pre-commit hooks (uv-lock, codegen) fail for the same reason  
3. mypy workflow section needs uv installed

## The Solution

Configure UV to use test.pypi when on release branches:

- Set `UV_INDEX_URL=https://test.pypi.org/simple/` (primary)
- Set `UV_EXTRA_INDEX_URL=https://pypi.org/simple/` (fallback)
- Set `UV_INDEX_STRATEGY=unsafe-best-match` to check both indexes

This allows `uv sync` to resolve common packages from PyPI and RC
versions from test.pypi.

## Additional Fixes

- Export UV env vars to `GITHUB_ENV` so pre-commit hooks inherit them
- Install uv in pre-commit workflow for mypy section
- Handle missing `type_checking` dependency group on release-0.3.x
- Regenerate uv.lock with RC versions for the release branch

## Changes

- Created reusable `install-llama-stack-client` action for configuration
- Modified `setup-runner` to set UV environment variables before sync
- Modified `pre-commit` workflow to configure client and export env vars
- Updated uv.lock with RC versions from test.pypi

This is a cherry-pick of commits afa9f0882, c86e6e906, 626639bee, and
081566321 from main, plus additional fixes for release branch
compatibility.

scripts/docker.sh

@@ -215,6 +215,16 @@ build_image() {
         --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

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

scripts/uv-run-with-index.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+set -euo pipefail
+
+# Detect current branch and target branch
+# In GitHub Actions, use GITHUB_REF/GITHUB_BASE_REF
+if [[ -n "${GITHUB_REF:-}" ]]; then
+  BRANCH="${GITHUB_REF#refs/heads/}"
+else
+  BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "")
+fi
+
+# For PRs, check the target branch
+if [[ -n "${GITHUB_BASE_REF:-}" ]]; then
+  TARGET_BRANCH="${GITHUB_BASE_REF}"
+else
+  TARGET_BRANCH=$(git rev-parse --abbrev-ref HEAD@{upstream} 2>/dev/null | sed 's|origin/||' || echo "")
+fi
+
+# Check if on a release branch or targeting one, or LLAMA_STACK_RELEASE_MODE is set
+IS_RELEASE=false
+if [[ "$BRANCH" =~ ^release-[0-9]+\.[0-9]+\.x$ ]]; then
+  IS_RELEASE=true
+elif [[ "$TARGET_BRANCH" =~ ^release-[0-9]+\.[0-9]+\.x$ ]]; then
+  IS_RELEASE=true
+elif [[ "${LLAMA_STACK_RELEASE_MODE:-}" == "true" ]]; then
+  IS_RELEASE=true
+fi
+
+# On release branches, use test.pypi as extra index for RC versions
+if [[ "$IS_RELEASE" == "true" ]]; then
+  export UV_EXTRA_INDEX_URL="https://test.pypi.org/simple/"
+  export UV_INDEX_STRATEGY="unsafe-best-match"
+fi
+
+# Run uv with all arguments passed through
+exec uv "$@"