feat: initial otko import

CONTRIBUTING.md

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+# Contributing
+
+Thanks for your interest. This project is in an early phase; the bar for
+incoming changes is on architecture cleanliness rather than feature
+breadth.
+
+## Dev setup
+
+```bash
+python -m venv .venv
+source .venv/bin/activate
+pip install -e ".[dev]"
+pre-commit install
+```
+
+## Before opening a PR
+
+```bash
+ruff check src tests
+ruff format src tests
+mypy src/otko/core src/otko/services
+pytest -m "not slow"
+```
+
+## Architectural rules (enforced in review)
+
+1. `core/` may not import Qt or `openseespy`. Period.
+2. `services/` may not import Qt.
+3. `views/` may not import `openseespy` directly — go through a service.
+4. Public functions and methods need type hints and a docstring.
+5. New domain entities go through Pydantic validation.
+6. Long-running operations (>50 ms) run off the GUI thread.
+
+## Commit style
+
+Conventional Commits — `feat:`, `fix:`, `refactor:`, `docs:`, `test:`,
+`chore:`, `ci:`.