feat(memory): add registerMemoryCommand for mosaic memory CLI surface

Adds mosaic memory CLI with four subcommands: search, stats,
insights list, and preferences list. Commands accept --db flag
(or MEMORY_DB_URL/DATABASE_URL env) to connect to pgvector or
keyword adapter. Smoke tests verify command wiring without DB.

Task: CU-05-04

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

packages/mosaic/src/cli.ts

@@ -3,6 +3,7 @@
 import { createRequire } from 'module';
 import { Command } from 'commander';
 import { registerQualityRails } from '@mosaicstack/quality-rails';
+import { registerMemoryCommand } from '@mosaicstack/memory';
 import { registerAgentCommand } from './commands/agent.js';
 import { registerMissionCommand } from './commands/mission.js';
 // prdy is registered via launch.ts
@@ -318,6 +319,10 @@ registerMissionCommand(program);
 
 registerQualityRails(program);
 
+// ─── memory ──────────────────────────────────────────────────────────────
+
+registerMemoryCommand(program);
+
 // ─── update ─────────────────────────────────────────────────────────────
 
 program