Add uv to PATH after install in CI

The uv installer places the binary in ~/.local/bin which isn't on
PATH by default in the act runner. Source the env file for the current
step and append to GITHUB_PATH for subsequent steps.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -45,6 +45,8 @@ jobs:
       - name: Install uv and Python
         run: |
           curl -LsSf https://astral.sh/uv/install.sh | sh
+          source "$HOME/.local/bin/env"
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
           uv python install 3.14
       - name: Install dependencies
         run: uv pip install --system --python 3.14 -e ".[dev]"