Add npm package for bd with native binaries (bd-febc)

Implements @beads/bd npm package for easy installation in Node.js
environments, especially Claude Code for Web.

Features:
- Automatic platform-specific binary download during postinstall
- CLI wrapper that invokes native bd binary
- Full feature parity with standalone bd
- Works with SessionStart hooks for auto-installation

Package structure:
- bin/bd.js: Node.js CLI wrapper
- scripts/postinstall.js: Downloads correct binary from GitHub releases
- scripts/test.js: Verification tests
- Comprehensive documentation (6 guides)

Published to npm: https://www.npmjs.com/package/@beads/bd

Benefits vs WASM:
- Full SQLite support (no custom VFS)
- Better performance (native vs WASM)
- Simpler implementation and maintenance
- All commands work identically

Closes bd-febc, bd-be7a, bd-e2e6, bd-f282, bd-87a0, bd-b54c

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

npm-package/PUBLISHING.md

@@ -0,0 +1,171 @@
+# Publishing @beads/bd to npm
+
+This guide covers how to publish the @beads/bd package to npm.
+
+## Prerequisites
+
+1. **npm account**: You need an npm account. Create one at https://www.npmjs.com/signup
+2. **@beads organization**: The package is scoped to `@beads`, so you need to either:
+   - Create the @beads organization on npm (if it doesn't exist)
+   - Be a member of the @beads organization with publish rights
+
+## Setup
+
+### 1. Login to npm
+
+```bash
+npm login
+```
+
+This will prompt for:
+- Username
+- Password
+- Email
+- OTP (if 2FA is enabled)
+
+### 2. Verify authentication
+
+```bash
+npm whoami
+```
+
+Should output your npm username.
+
+### 3. Create organization (if needed)
+
+If the `@beads` organization doesn't exist:
+
+```bash
+npm org create beads
+```
+
+Or manually at: https://www.npmjs.com/org/create
+
+## Publishing
+
+### 1. Update version (if needed)
+
+The version in `package.json` should match the beads release version.
+
+```bash
+# Edit package.json manually or use npm version
+npm version patch  # or minor, major
+```
+
+### 2. Test the package
+
+```bash
+# From the npm-package directory
+npm test
+
+# Test installation locally
+npm link
+
+# Verify the global install works
+bd version
+```
+
+### 3. Publish to npm
+
+For the first publish:
+
+```bash
+# Publish as public (scoped packages are private by default)
+npm publish --access public
+```
+
+For subsequent publishes:
+
+```bash
+npm publish
+```
+
+### 4. Verify publication
+
+```bash
+# Check the package page
+open https://www.npmjs.com/package/@beads/bd
+
+# Try installing it
+npm install -g @beads/bd
+bd version
+```
+
+## Publishing Workflow
+
+The typical workflow when a new beads version is released:
+
+1. **Wait for GitHub release**: Ensure the new version is released on GitHub with binaries
+2. **Update package.json**: Update version to match the GitHub release
+3. **Test locally**: Run `npm install` and `npm test` to ensure binaries download correctly
+4. **Publish**: Run `npm publish --access public` (or just `npm publish` after first release)
+5. **Verify**: Install globally and test
+
+## Automation (Future)
+
+In the future, this could be automated with GitHub Actions:
+
+```yaml
+# .github/workflows/publish-npm.yml
+name: Publish to npm
+on:
+  release:
+    types: [published]
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+        with:
+          node-version: '18'
+          registry-url: 'https://registry.npmjs.org'
+      - run: cd npm-package && npm publish --access public
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+```
+
+## Troubleshooting
+
+### "EEXIST: package already published"
+
+You're trying to publish a version that already exists. Bump the version:
+
+```bash
+npm version patch
+npm publish
+```
+
+### "ENEEDAUTH: need auth"
+
+You're not logged in:
+
+```bash
+npm login
+npm whoami  # verify
+```
+
+### "E403: forbidden"
+
+You don't have permission to publish to @beads. Either:
+- Create the organization
+- Ask the organization owner to add you
+- Change the package name to something you own
+
+### Binary download fails during postinstall
+
+The version in package.json doesn't match a GitHub release, or the release doesn't have the required binary assets.
+
+Check: https://github.com/steveyegge/beads/releases/v{VERSION}
+
+## Version Sync
+
+Keep these in sync:
+- `npm-package/package.json` version
+- GitHub release tag (e.g., `v0.21.5`)
+- Beads binary version
+
+The postinstall script downloads binaries from:
+```
+https://github.com/steveyegge/beads/releases/download/v{VERSION}/beads_{VERSION}_{platform}_{arch}.{ext}
+```