Fastify + single-page frontend on shared @nexusai/core. Reads the same SQLite
journal and media dir. Features: usage stats (by provider/capability/day),
content gallery (image/audio/video with local file serving + path-traversal
guard), provider CRUD with encrypted keys (masked in UI), enable/disable,
set-default, and real key validation via zero-cost /media/models call.
Adds Journal.getById and NordRouterMediaProvider.checkKey to core.