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.

.github/actions/setup-runner/action.yml

@@ -18,25 +18,35 @@ runs:
         python-version: ${{ inputs.python-version }}
         version: 0.7.6
 
+    - name: Configure client installation
+      id: client-config
+      uses: ./.github/actions/install-llama-stack-client
+      with:
+        client-version: ${{ inputs.client-version }}
+
     - name: Install dependencies
       shell: bash
+      env:
+        UV_EXTRA_INDEX_URL: ${{ steps.client-config.outputs.uv-extra-index-url }}
+        UV_INDEX_STRATEGY: ${{ steps.client-config.outputs.uv-extra-index-url && 'unsafe-best-match' || '' }}
       run: |
+        # Export UV env vars to GITHUB_ENV so they persist across steps
+        if [ -n "$UV_EXTRA_INDEX_URL" ]; then
+          echo "UV_EXTRA_INDEX_URL=$UV_EXTRA_INDEX_URL" >> $GITHUB_ENV
+          echo "UV_INDEX_STRATEGY=$UV_INDEX_STRATEGY" >> $GITHUB_ENV
+          echo "Exported UV environment variables for subsequent steps"
+        fi
+
         echo "Updating project dependencies via uv sync"
         uv sync --all-groups
 
         echo "Installing ad-hoc dependencies"
         uv pip install faiss-cpu
 
-        # Install llama-stack-client-python based on the client-version input
-        if [ "${{ inputs.client-version }}" = "latest" ]; then
-          echo "Installing latest llama-stack-client-python from main branch"
-          uv pip install git+https://github.com/llamastack/llama-stack-client-python.git@main
-        elif [ "${{ inputs.client-version }}" = "published" ]; then
-          echo "Installing published llama-stack-client-python from PyPI"
-          uv pip install llama-stack-client
-        else
-          echo "Invalid client-version: ${{ inputs.client-version }}"
-          exit 1
+        # Install specific client version after sync if needed
+        if [ "${{ steps.client-config.outputs.install-after-sync }}" = "true" ]; then
+          echo "Installing llama-stack-client from: ${{ steps.client-config.outputs.install-source }}"
+          uv pip install ${{ steps.client-config.outputs.install-source }}
         fi
 
         echo "Installed llama packages"