feat: add build system, stubs, and npm packaging — openclaude is now runnable

- package.json with all 70+ dependencies
- Bun build script with feature flag shims, native module stubs, otel externals
- Stubs for ~15 missing source files (snapshot gaps)
- tsconfig.json for TypeScript
- bin/openclaude entry point
- Builds to single 19MB dist/cli.mjs
- Verified: --version and --help work

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

src/components/agents/SnapshotUpdateDialog.tsx

@@ -0,0 +1,3 @@
+// Stub
+import React from 'react'
+export function SnapshotUpdateDialog(_props: unknown) { return null }