Add CLAUDE.md with pre-push checklist and changeset rule

Encodes the expected workflow so future Claude sessions follow it without
re-deriving it from scratch:
- run typecheck and build before pushing
- add a changeset when src/ changes affect users
- never push to main; branch + PR
- public API boundaries that need explicit approval to change
- things to never do (publish/tag by hand, edit generated changesets,
  add runtime deps, rewrite history)

Author: scoobynko

CLAUDE.md

@@ -0,0 +1,50 @@
+# Repository rules for Claude
+
+Read this before making any change to this repo.
+
+## Pre-push checklist
+
+Before you push a branch (any branch), run these and make sure they all pass:
+
+1. `npm run typecheck` — must exit 0.
+2. `npm run build` — must succeed and produce `dist/index.mjs`, `dist/index.d.ts`, `dist/styles.css`.
+
+Do not push if either fails. Fix the root cause; do not silence errors.
+
+## Changeset rule
+
+If the change modifies anything under `src/` that affects users of the published package (new/removed/changed prop, behavior change, bug fix that reaches runtime, CSS that changes visuals), you MUST add a changeset before opening the PR:
+
+```
+npx changeset
+```
+
+- Bump type: `patch` for bug fixes, `minor` for additive features, `major` for breaking changes to the public API (`SnakeLoader`, `SnakeLoaderProps`, `Theme`, `Colors`, `Effects`).
+- Summary: one line, written from the consumer's perspective (what changed for them, not what you did internally).
+
+Skip the changeset for: docs-only edits, CI/workflow changes, `.gitignore`, `CLAUDE.md`, internal refactors with zero observable effect, tooling config that doesn't change the tarball.
+
+When in doubt, add one. An extra changeset is cheap; a missing one means a fix ships unversioned.
+
+## Branch + PR flow
+
+- `main` is protected. Never push to it directly — the ruleset will reject it.
+- Work in a short-named branch (`fix/...`, `feat/...`, `chore/...`, `docs/...`).
+- Open a PR with `gh pr create`. The user merges.
+- After merge, the Release workflow either opens a "Version Packages" PR (if changesets are pending) or no-ops.
+
+## Public API — do not change without the user's explicit approval
+
+These are part of the package's public contract. Changing any of them is a major bump and needs a conversation first:
+
+- Props: `theme`, `cellSize`, `speed`, `colors`, `effects`, `paused`, `className`, `style`, `aria-label`.
+- Exports: `SnakeLoader`, `SnakeLoaderProps`, `Theme`, `Colors`, `Effects`.
+- Observable behavior: 8×8 grid (`GRID_SIZE`), initial snake length of 2 (`INITIAL_LENGTH`), death flicker duration of 12 ticks (`DYING_TICKS`), weighted-random pathing with 60% straight persistence, default `cellSize: 3`, default `speed: 10`.
+
+## Things to never do
+
+- Do not commit `dist/` or `node_modules/`.
+- Do not run `npm publish`, `npm version`, or create release tags by hand — the Release workflow owns these.
+- Do not edit `.changeset/*.md` files that the "Version Packages" PR generated. They're produced by `changeset version` and deleted on release.
+- Do not add runtime dependencies. This package advertises zero deps.
+- Do not use `git push --force`, `git reset --hard`, or `git commit --amend` on pushed commits.