Add CLAUDE.md and gitignore .claude/ directory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: paustin01

.gitignore

@@ -33,3 +33,6 @@ Thumbs.db
 *.tmp
 .notes
 .windsurfrules
+
+# Claude Code
+.claude/

CLAUDE.md

@@ -0,0 +1,46 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## What This Is
+
+Versioner GitHub Action - a TypeScript GitHub Action that sends build and deployment events to the Versioner API. Node.js 20, @actions/core, Axios.
+
+## Cross-Repo Context
+
+This repo is part of the Versioner ecosystem. Before starting work:
+- Read `/Users/phil.austin/projects/versioner-repos/versioner-dev-docs/status.md` for current status
+- Read relevant feature docs from `/Users/phil.austin/projects/versioner-repos/versioner-dev-docs/features/`
+- Update `status.md` as you complete tasks
+
+## Build & Test Commands
+
+All commands use `just` (run `just` to list all):
+
+```bash
+just setup_local_dev    # npm install
+just build              # ncc build to dist/index.js (self-contained bundle)
+just run_tests          # Jest (80% coverage threshold)
+just test_coverage      # Jest with coverage report
+just lint               # ESLint (strict: explicit return types, no any)
+just format             # Prettier
+just ci                 # format -> lint -> build -> test
+```
+
+The `dist/` directory is committed (GitHub Actions requires it).
+
+## Architecture
+
+- `src/index.ts` - Entry point; routes to build or deployment event handling based on `event_type` input
+- `src/inputs.ts` - Input validation and parsing (from GitHub Actions inputs or env vars)
+- `src/api-client.ts` - HTTP client for Versioner API with error handling for preflight rejections (409, 423, 428)
+- `src/github-context.ts` - Extracts GitHub metadata (repo, SHA, branch, actor, workflow URL) and auto-captures env vars with `vi_gh_` prefix
+- `src/types.ts` - TypeScript interfaces for payloads and responses
+- `action.yml` - Action definition with inputs/outputs
+
+## Conventions
+
+- Follow existing code patterns and style
+- Blank lines must be completely empty (no whitespace-only lines)
+- Add tests for new features; ensure tests pass before committing
+- Prefer editing existing files over creating new ones