Require an API key or {env:VAR} on client and server, add edit/prefill for
existing custom providers, save auth before config, and surface incomplete
auth plus disconnect after partial failures. Add VS Code parity tests and
drop the unused allProvidersConnected locale key.
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>
Allow Settings → Providers to define custom providers (id, name, base URL,
API key, models, headers) without code changes. Persist config via OpenCode
layers, store keys through auth.set, and keep web/VS Code parity.
Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>
