Remove retired Command Code, Discord, and Telegram integration entries, search targets, and documentation. Keep Command Code provider usage and logo support available through normalized provider ID aliases.
Add a Settings → Integrations page for installing and managing the three
supported OpenCode provider plugins (Claude Code, Command Code, Cursor),
with search, i18n, and plugin-registry status wiring.
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>