Initial project outline

- package.json (ESM, bin entry)
- bin/delta-backup.js — entrypoint
- lib/args.js — CLI arg parsing via Node parseArgs
- lib/config.js — config file merging + required path guards
- lib/spawn.js — safe process spawning (no shell strings)
- lib/state.js — sequence number + phase state management
- lib/backends/zstd.js — zstd delta backend
- lib/backends/index.js — backend registry
- lib/commands/run.js — full run skeleton (phases 1-3 wired, 4-6 stubbed)
- lib/commands/status.js — status command

bin/delta-backup.js

@@ -0,0 +1,22 @@
+#!/usr/bin/env node
+import { parseArgs } from '../lib/args.js';
+import { loadConfig } from '../lib/config.js';
+import { runCommand } from '../lib/commands/run.js';
+import { statusCommand } from '../lib/commands/status.js';
+
+const args = parseArgs(process.argv.slice(2));
+const config = await loadConfig(args);
+
+const commands = {
+  run:    runCommand,
+  status: statusCommand,
+};
+
+const cmd = commands[config.command];
+if (!cmd) {
+  console.error(`Unknown command: ${config.command}`);
+  console.error('Available commands: run, status');
+  process.exit(1);
+}
+
+await cmd(config);