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/workflows/pre-commit.yml

@@ -111,3 +111,58 @@ jobs:
             echo "$unstaged_files"
             exit 1
           fi
+
+      - name: Install uv for mypy
+        uses: astral-sh/setup-uv@6b9c6063abd6010835644d4c2e1bef4cf5cd0fca # v6.0.1
+        with:
+          python-version: "3.12"
+          version: 0.7.6
+
+      - name: Configure client installation
+        id: client-config
+        uses: ./.github/actions/install-llama-stack-client
+
+      - name: Sync dev dependencies for mypy
+        env:
+          UV_EXTRA_INDEX_URL: ${{ steps.client-config.outputs.uv-extra-index-url }}
+          UV_INDEX_STRATEGY: ${{ steps.client-config.outputs.uv-extra-index-url && 'unsafe-best-match' || '' }}
+        run: |
+          # Check if type_checking group exists, otherwise just use dev
+          if grep -q "type.checking" pyproject.toml; then
+            echo "Found type_checking group, syncing with both groups"
+            uv sync --group dev --group type_checking
+            MYPY_CMD="uv run --group dev --group type_checking mypy"
+          else
+            echo "No type_checking group found, syncing with dev only"
+            uv sync --group dev
+            MYPY_CMD="uv run --group dev mypy"
+          fi
+
+          # Install specific client version after sync if needed
+          if [ "${{ steps.client-config.outputs.install-after-sync }}" = "true" ]; then
+            echo "Installing llama-stack-client from: ${{ steps.client-config.outputs.install-source }}"
+            uv pip install ${{ steps.client-config.outputs.install-source }}
+          fi
+
+          echo "MYPY_CMD=$MYPY_CMD" >> $GITHUB_ENV
+
+      - name: Run mypy (full type checking)
+        env:
+          UV_EXTRA_INDEX_URL: ${{ steps.client-config.outputs.uv-extra-index-url }}
+          UV_INDEX_STRATEGY: ${{ steps.client-config.outputs.uv-extra-index-url && 'unsafe-best-match' || '' }}
+        run: |
+          set +e
+          output=$($MYPY_CMD 2>&1)
+          status=$?
+
+          # If mypy isn't available (common on older release branches), skip gracefully
+          if echo "$output" | grep -q "Failed to spawn.*mypy"; then
+            echo "::warning::mypy not available, skipping type checking (expected on release-0.3.x)"
+            exit 0
+          fi
+
+          echo "$output"
+          if [ $status -ne 0 ]; then
+            echo "::error::Full mypy failed. Reproduce locally with 'uv run pre-commit run mypy-full --hook-stage manual --all-files'."
+          fi
+          exit $status