Add Homarr provider proxy foundation

apps/workshop/.env.example

@@ -7,6 +7,11 @@ HOMARR_WEBSITE_URL=http://127.0.0.1:3003
 WORKSHOP_API_URL=http://127.0.0.1:8090
 WORKSHOP_WEB_URL=http://127.0.0.1:3003/workshop
 
+# Optional Homarr provider. The upstream key stays only in the Workshop server.
+# OPENROUTER_API_KEY=
+HOMARR_AI_DAILY_REQUEST_LIMIT=50
+# HOMARR_AI_OPENROUTER_BASE_URL=https://openrouter.ai/api/v1
+
 # Optional local GitHub OAuth application.
 # GITHUB_CLIENT_ID=
 # GITHUB_CLIENT_SECRET=