fix(ci): install pytest when pyproject.toml is missing

Root cause: ci.yml test job creates .venv but skips dev install when
pyproject.toml is absent, leaving pytest uninstalled. Then .venv/bin/pytest
fails with 'No such file or directory'.

Fix: Install pytest directly when no pyproject.toml, and use /tmp path
to avoid workspace pollution.

.gitea/workflows/ci.yml

@@ -47,17 +47,17 @@ jobs:
 
       - name: Setup Python
         run: |
-          python3 -m venv .venv
+          python3 -m venv /tmp/ci-venv-test
           if [ -f pyproject.toml ]; then
-            .venv/bin/pip install --quiet -e ".[dev]"
+            /tmp/ci-venv-test/bin/pip install --quiet -e ".[dev]"
           else
-            echo "No pyproject.toml, skipping dev install"
+            /tmp/ci-venv-test/bin/pip install --quiet pytest
           fi
 
       - name: Run tests (exclude E2E)
         run: |
           if [ -d tests ]; then
-            .venv/bin/pytest tests/ -m "not e2e" -x -q
+            /tmp/ci-venv-test/bin/pytest tests/ -m "not e2e" -x -q
           else
             echo "No tests/ directory, skipping tests"
           fi