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/package.json

@@ -0,0 +1,52 @@
+{
+  "name": "@beads/bd",
+  "version": "0.21.5",
+  "description": "Beads issue tracker - lightweight memory system for coding agents with native binary support",
+  "main": "bin/bd.js",
+  "bin": {
+    "bd": "bin/bd.js"
+  },
+  "scripts": {
+    "postinstall": "node scripts/postinstall.js",
+    "test": "node scripts/test.js"
+  },
+  "keywords": [
+    "issue-tracker",
+    "dependency-tracking",
+    "ai-agent",
+    "coding-agent",
+    "claude",
+    "sqlite",
+    "git",
+    "project-management"
+  ],
+  "author": "Steve Yegge",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/steveyegge/beads.git",
+    "directory": "npm-package"
+  },
+  "bugs": {
+    "url": "https://github.com/steveyegge/beads/issues"
+  },
+  "homepage": "https://github.com/steveyegge/beads#readme",
+  "engines": {
+    "node": ">=14.0.0"
+  },
+  "os": [
+    "darwin",
+    "linux",
+    "win32"
+  ],
+  "cpu": [
+    "x64",
+    "arm64"
+  ],
+  "files": [
+    "bin/",
+    "scripts/",
+    "README.md",
+    "LICENSE"
+  ]
+}