docs: clean up README, extract CONTRIBUTING.md (#637)

* docs: clean up README, extract CONTRIBUTING.md

- Remove stale "buckaroo has moved to" notice
- Fix ~10 links from paddymul/buckaroo to buckaroo-data/buckaroo
- Add PyPI, CI, and license badges
- Fix typos (rwos, Bucakroo, dangling backtick)
- Consolidate duplicate autocleaning sections
- Modernize quick start (pip install, clean code block)
- Promote Polars from "optional" footnote to first-class mention
- Move dev setup, Storybook, Playwright, UV, and release instructions
  to CONTRIBUTING.md (was ~120 lines of README)
- Fix broken markdown formatting

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address Codex review comments on PR #637

- Add missing `cd packages/buckaroo-js-core` before `pnpm build-storybook`
- Update release process docs to reflect workflow_dispatch flow (not manual tag-push)
- Update CLAUDE.md release section to match

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: paddymul

CLAUDE.md

@@ -58,6 +58,5 @@ Runs on push to main and PRs. Key jobs: LintPython, TestJS, BuildWheel, TestPyth
 ## Release Process
 
 1. Update CHANGELOG.md
-2. Tag (no 'v' prefix): `git tag 0.12.13`
-3. Push tag: `git push origin tag 0.12.13`
-4. Release workflow generates notes and publishes to PyPI
+2. Trigger the **Release** workflow via GitHub Actions (`workflow_dispatch`), choosing `patch`, `minor`, or `major`
+3. The workflow bumps the version in `pyproject.toml`, creates the tag, builds, publishes to PyPI, and creates a GitHub release

CONTRIBUTING.md

@@ -0,0 +1,103 @@
+# Contributing to Buckaroo
+
+We love contributions! This guide covers development setup, building, testing, and releasing.
+
+## Development setup
+
+### Prerequisites
+- [uv](https://docs.astral.sh/uv/) for Python dependency management
+- [pnpm](https://pnpm.io/) for JavaScript dependency management
+- Node.js >= 18
+- Python >= 3.11
+
+### Python
+
+```bash
+git clone https://github.com/buckaroo-data/buckaroo.git
+cd buckaroo
+uv sync --dev --all-extras
+```
+
+### JavaScript
+
+```bash
+cd packages/buckaroo-js-core
+pnpm install
+```
+
+### Full build (JS + Python wheel)
+
+```bash
+./scripts/full_build.sh
+```
+
+
+## Running tests
+
+### Python
+
+```bash
+uv run pytest tests/unit/ -v
+uv run ruff check --fix
+```
+
+### JavaScript
+
+```bash
+cd packages/buckaroo-js-core
+pnpm test
+```
+
+### Storybook (component development)
+
+```bash
+cd packages/buckaroo-js-core
+pnpm storybook
+# open http://localhost:6006
+```
+
+Build a static Storybook site:
+```bash
+cd packages/buckaroo-js-core
+pnpm build-storybook
+```
+
+### Playwright (UI tests against Storybook)
+
+Install browsers:
+```bash
+cd packages/buckaroo-js-core
+pnpm exec playwright install
+```
+
+Run tests:
+```bash
+pnpm test:pw --reporter=line
+```
+
+Useful variants:
+```bash
+pnpm test:pw:headed   # visible browser
+pnpm test:pw:ui       # Playwright UI
+pnpm test:pw:report   # open HTML report
+```
+
+
+## Adding dependencies
+
+```bash
+uv add <package>                              # main dependency
+uv add --group <group> <package>              # extras group
+```
+
+
+## Release process
+
+1. Update `CHANGELOG.md`
+2. Trigger the **Release** workflow via GitHub Actions (`workflow_dispatch`), choosing `patch`, `minor`, or `major`
+3. The workflow bumps the version in `pyproject.toml`, creates the tag, builds, publishes to PyPI, and creates a GitHub release
+
+
+## Reporting issues
+
+We welcome [issue reports](https://github.com/buckaroo-data/buckaroo/issues). Please choose the proper issue template so we get the necessary information.