Add native Keito GitHub Action

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: npm
+      - run: npm ci
+      - run: npm run typecheck
+      - run: npm test
+      - run: npm run check-dist

.gitignore

@@ -0,0 +1,5 @@
+node_modules/
+coverage/
+lib/
+.DS_Store
+*.log

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# Contributing
+
+## Local Setup
+
+```bash
+npm install
+npm test
+npm run typecheck
+npm run build
+```
+
+## Release Build
+
+The action runs from `dist/index.js`, so source changes must be bundled before a
+release.
+
+```bash
+npm run build
+git diff -- dist/index.js
+```
+
+## Design Notes
+
+- Keep the action dependency-light.
+- Preserve compatibility with the Keito CLI v2 API contract.
+- Add tests for every new event parser or billing heuristic.
+- Do not log API keys, GitHub tokens, or full request headers.