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/package.json

@@ -31,6 +31,7 @@
     "@mosaicstack/config": "workspace:*",
     "@mosaicstack/forge": "workspace:*",
     "@mosaicstack/macp": "workspace:*",
+    "@mosaicstack/memory": "workspace:*",
     "@mosaicstack/prdy": "workspace:*",
     "@mosaicstack/quality-rails": "workspace:*",
     "@mosaicstack/queue": "workspace:*",