feat(log): add registerLogCommand for mosaic log CLI surface

Adds mosaic log tail|search|export|level subcommands to @mosaicstack/log,
wires registerLogCommand into the root mosaic CLI, and ships a smoke test
that asserts command structure without opening the database. Ref CU-05-07.

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

packages/mosaic/package.json

@@ -29,6 +29,7 @@
   "dependencies": {
     "@mosaicstack/config": "workspace:*",
     "@mosaicstack/forge": "workspace:*",
+    "@mosaicstack/log": "workspace:*",
     "@mosaicstack/macp": "workspace:*",
     "@mosaicstack/prdy": "workspace:*",
     "@mosaicstack/quality-rails": "workspace:*",