feat(wave3): add @mosaic/cli — unified mosaic CLI entry point

- Root Commander program with version + description
- Subcommand groups: coord, prdy, queue, quality-rails
- Single `mosaic` binary entry point
- Depends on all @mosaic/* workspace packages

packages/cli/tests/root-command.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest';
+
+import { rootCommand } from '../src/root-command.js';
+
+describe('rootCommand', () => {
+  it('registers all top-level subcommand groups', () => {
+    const registeredSubcommands = rootCommand.commands
+      .map((command) => command.name())
+      .sort((left, right) => left.localeCompare(right));
+
+    expect(registeredSubcommands).toEqual([
+      'coord',
+      'prdy',
+      'quality-rails',
+      'queue',
+    ]);
+  });
+});