feat: add StepFun and Nous Portal provider support (#140)

- Add StepFun provider (API key auth, STEPFUN_API_KEY)
- Add Nous Portal provider with full OAuth device code flow
  (device code request → poll for token → mint agent key → save to auth.json)
- Add NousLoginModal component for OAuth UI (user code display + verification link)
- Update ProviderFormModal to handle Nous OAuth flow (hide API key fields)
- Add nous-auth backend controller and routes
- Update PROVIDER_ENV_MAP with stepfun and nous entries
- Add i18n translations for Nous OAuth in all 8 locales

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/server/src/routes/hermes/nous-auth.ts

@@ -0,0 +1,8 @@
+import Router from '@koa/router'
+import * as ctrl from '../../controllers/hermes/nous-auth'
+
+export const nousAuthRoutes = new Router()
+
+nousAuthRoutes.post('/api/hermes/auth/nous/start', ctrl.start)
+nousAuthRoutes.get('/api/hermes/auth/nous/poll/:sessionId', ctrl.poll)
+nousAuthRoutes.get('/api/hermes/auth/nous/status', ctrl.status)