ci: add uv setup to pre-commit workflow

The ty hook requires uv to run `uv run ty check src/`, but the
workflow was missing the uv installation step, causing hook
failures with exit code 127 (uv: command not found).

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

.github/workflows/pre-commit.yml

@@ -16,4 +16,5 @@ jobs:
       - uses: actions/setup-python@v6
         with:
           python-version: '3.12'
+      - uses: astral-sh/setup-uv@v6
       - uses: pre-commit/action@v3.0.1