feat(storage): add registerStorageCommand for mosaic storage CLI surface

Implements CU-05-02: adds `mosaic storage` command group with subcommands
status, tier show, tier switch, export, import, and migrate. Pragmatic
stubs print actionable instructions for unimplemented export/import tiers.

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

packages/mosaic/src/cli.ts

@@ -5,6 +5,7 @@ import { Command } from 'commander';
 import { registerBrainCommand } from '@mosaicstack/brain';
 import { registerQualityRails } from '@mosaicstack/quality-rails';
 import { registerQueueCommand } from '@mosaicstack/queue';
+import { registerStorageCommand } from '@mosaicstack/storage';
 import { registerAgentCommand } from './commands/agent.js';
 import { registerMissionCommand } from './commands/mission.js';
 // prdy is registered via launch.ts
@@ -347,6 +348,10 @@ registerQualityRails(program);
 
 registerQueueCommand(program);
 
+// ─── storage ─────────────────────────────────────────────────────────────
+
+registerStorageCommand(program);
+
 // ─── update ─────────────────────────────────────────────────────────────
 
 program