- Add 'cohere' to DEFAULT_PROVIDERS and PLANNING_PROVIDERS arrays in admin.js
- Add Cohere option to provider limits dropdown in admin.html
- Add 'cohere' to DEFAULT_PROVIDER_SEEDS, PLANNING_PROVIDERS, and KNOWN_USAGE_PROVIDERS in server.js
Cohere was already integrated in the opencode backend (SDK installed, provider registered, icons defined). These changes make it available in the admin panel for build message configuration.