feat: add project release and run tests skills documentation

- Introduced SKILL.md files for project release and running tests in the duty-teller project.
- Documented the project release workflow, including steps for updating CHANGELOG, committing changes, and tagging releases.
- Provided instructions for running backend (pytest) and frontend (Vitest) tests, including prerequisites and failure handling.
- Enhanced user guidance for verifying changes and ensuring test coverage.

.cursor/skills/run-tests/SKILL.md

@@ -0,0 +1,60 @@
+---
+name: run-tests
+description: Runs backend (pytest) and frontend (Vitest) tests for the duty-teller project. Use when the user asks to run tests, verify changes, or run pytest/vitest.
+---
+
+# Run tests
+
+## When to use
+
+- User asks to "run tests", "run the test suite", or "verify tests pass".
+- After making code changes and user wants to confirm nothing is broken.
+- User explicitly asks for backend tests (pytest) or frontend tests (vitest/npm test).
+
+## Backend tests (Python)
+
+From the **repository root**:
+
+```bash
+pytest
+```
+
+If imports fail, set `PYTHONPATH`:
+
+```bash
+PYTHONPATH=. pytest
+```
+
+- Config: `pyproject.toml` → `[tool.pytest.ini_options]` (coverage on `duty_teller`, 80% gate, asyncio mode).
+- Tests live in `tests/`.
+
+## Frontend tests (Next.js / Vitest)
+
+From the **repository root**:
+
+```bash
+cd webapp-next && npm test
+```
+
+- Runner: Vitest (`vitest run`); env: jsdom; React Testing Library.
+- Config: `webapp-next/vitest.config.ts`; setup: `webapp-next/src/test/setup.ts`.
+
+## Running both
+
+To run backend and frontend tests in sequence:
+
+```bash
+pytest && (cd webapp-next && npm test)
+```
+
+If the user did not specify "backend only" or "frontend only", run both and report results for each.
+
+## Scope
+
+- **Single file or dir:** `pytest path/to/test_file.py` or `pytest path/to/test_dir/`. For frontend, use Vitest’s path args as per its docs (e.g. under `webapp-next/`).
+- **Verbosity:** Use `pytest -v` if the user wants more detail.
+
+## Failures
+
+- Do not send raw exception strings from tests to the user; summarize failures and point to failing test names/locations.
+- If pytest fails with import errors, suggest `PYTHONPATH=. pytest` and ensure the venv is activated and dev deps are installed (`pip install -r requirements-dev.txt` or `pip install -e ".[dev]"`).