refactor: move UV index config into pre-commit hook

Make uv-lock pre-commit hook smart about release branches by wrapping it
in a script that detects release branches and sets UV_EXTRA_INDEX_URL.

This allows the same pre-commit config to work locally and in CI without
special environment variable setup in workflows.

Changes:
- Add scripts/pre-commit-uv-lock.sh wrapper that detects release branches
- Move uv-lock from astral-sh/uv-pre-commit to local hook using wrapper
- Remove UV env var setup from pre-commit workflow (hook handles it)
- Regenerate uv.lock with test.pypi as extra index (not primary)

.github/workflows/pre-commit.yml

@@ -49,19 +49,6 @@ jobs:
         run: npm ci
         working-directory: llama_stack/ui
 
-      - name: Configure client installation
-        id: client-config-precommit
-        uses: ./.github/actions/install-llama-stack-client
-
-      - name: Export UV environment variables
-        run: |
-          if [ -n "${{ steps.client-config-precommit.outputs.uv-extra-index-url }}" ]; then
-            echo "UV_EXTRA_INDEX_URL=${{ steps.client-config-precommit.outputs.uv-extra-index-url }}" >> $GITHUB_ENV
-            echo "UV_INDEX_STRATEGY=unsafe-best-match" >> $GITHUB_ENV
-            echo "Setting UV_EXTRA_INDEX_URL to ${{ steps.client-config-precommit.outputs.uv-extra-index-url }}"
-            echo "Setting UV_INDEX_STRATEGY to unsafe-best-match"
-          fi
-
       - name: Run pre-commit
         id: precommit
         uses: pre-commit/action@2c7b3805fd2a0fd8c1884dcaebf91fc102a13ecd # v3.0.1