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>

bin/openclaude

@@ -0,0 +1,32 @@
+#!/usr/bin/env node
+
+/**
+ * OpenClaude — Claude Code with any LLM
+ *
+ * If dist/cli.mjs exists (built), run that.
+ * Otherwise, tell the user to build first or use `bun run dev`.
+ */
+
+import { existsSync } from 'fs'
+import { join, dirname } from 'path'
+import { fileURLToPath } from 'url'
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+const distPath = join(__dirname, '..', 'dist', 'cli.mjs')
+
+if (existsSync(distPath)) {
+  await import(distPath)
+} else {
+  console.error(`
+  openclaude: dist/cli.mjs not found.
+
+  Build first:
+    bun run build
+
+  Or run directly with Bun:
+    bun run dev
+
+  See README.md for setup instructions.
+`)
+  process.exit(1)
+}