fix(ci): create virtual environment before uv pip install

Add 'uv venv' step before 'uv pip install' in both tests and prek-hook
jobs to fix "No virtual environment found" error. The uv package manager
requires an active virtual environment for pip operations.

Author: claude

.github/workflows/tests.yml

@@ -30,6 +30,8 @@ jobs:
         uses: astral-sh/setup-uv@v7
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Create virtual environment
+        run: uv venv
       - name: Install Package
         run: uv pip install ".[test]"
       - name: Run pytest
@@ -47,6 +49,8 @@ jobs:
         uses: j178/prek-action@v1
         with:
           install-only: true
+      - name: Create virtual environment
+        run: uv venv
       - name: Install Package
         run: uv pip install ".[test]"
       - name: run prek with plugin