ci: Fix release workflow - install uv and initialize submodules

Fixes release build failures:

1. Install uv for bootstrap skill tests
   - Added step to install uv from astral.sh
   - Fixes 7 bootstrap test failures (test_bootstrap_skill*.py)

2. Initialize git submodules
   - Added 'submodules: recursive' to checkout action
   - Fixes test_cli_all_flag_lists_configs (needs configs submodule)

This ensures all 1200+ tests pass in release builds.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -14,12 +14,19 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+      with:
+        submodules: 'recursive'
 
     - name: Set up Python
       uses: actions/setup-python@v4
       with:
         python-version: '3.10'
 
+    - name: Install uv
+      run: |
+        curl -LsSf https://astral.sh/uv/install.sh | sh
+        echo "$HOME/.cargo/bin" >> $GITHUB_PATH
+
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip