feat: add setup script skeleton

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

Co-Authored-By: Claude Opus 4.5 <[e-mail]>

package.json

···
   "scripts": {
     "dev": "wrangler dev",
     "deploy": "wrangler deploy",
-    "test": "node --test test/*.test.js"
+    "test": "node --test test/*.test.js",
+    "setup": "node scripts/setup.js"
   }
 }

scripts/setup.js

···
+#!/usr/bin/env node
+
+/**
+ * PDS Setup Script
+ *
+ * Registers a did:plc, initializes the PDS, and notifies the relay.
+ * Zero dependencies - uses Node.js built-ins only.
+ *
+ * Usage: node scripts/setup.js --handle alice --pds https://your-pds.workers.dev
+ */
+
+import { webcrypto } from 'crypto'
+
+// === ARGUMENT PARSING ===
+
+function parseArgs() {
+  const args = process.argv.slice(2)
+  const opts = {
+    handle: null,
+    pds: null,
+    plcUrl: 'https://plc.directory',
+    relayUrl: 'https://bsky.network'
+  }
+
+  for (let i = 0; i < args.length; i++) {
+    if (args[i] === '--handle' && args[i + 1]) {
+      opts.handle = args[++i]
+    } else if (args[i] === '--pds' && args[i + 1]) {
+      opts.pds = args[++i]
+    } else if (args[i] === '--plc-url' && args[i + 1]) {
+      opts.plcUrl = args[++i]
+    } else if (args[i] === '--relay-url' && args[i + 1]) {
+      opts.relayUrl = args[++i]
+    }
+  }
+
+  if (!opts.handle || !opts.pds) {
+    console.error('Usage: node scripts/setup.js --handle <handle> --pds <pds-url>')
+    console.error('')
+    console.error('Options:')
+    console.error('  --handle      Handle name (e.g., "alice")')
+    console.error('  --pds         PDS URL (e.g., "https://atproto-pds.chad-53c.workers.dev")')
+    console.error('  --plc-url     PLC directory URL (default: https://plc.directory)')
+    console.error('  --relay-url   Relay URL (default: https://bsky.network)')
+    process.exit(1)
+  }
+
+  return opts
+}
+
+// === MAIN ===
+
+async function main() {
+  const opts = parseArgs()
+
+  console.log('PDS Federation Setup')
+  console.log('====================')
+  console.log(`Handle: ${opts.handle}`)
+  console.log(`PDS: ${opts.pds}`)
+  console.log(`PLC: ${opts.plcUrl}`)
+  console.log(`Relay: ${opts.relayUrl}`)
+  console.log('')
+
+  // TODO: Implement in subsequent tasks
+  console.log('TODO: Generate keypair')
+  console.log('TODO: Register DID:PLC')
+  console.log('TODO: Initialize PDS')
+  console.log('TODO: Notify relay')
+}
+
+main().catch(err => {
+  console.error('Error:', err.message)
+  process.exit(1)
+})