security: stop tracking env files; admin gate via VITE_SITE_ADMIN_GATE; Redis/cache/docs

Remove InfoGenie-frontend and Go .env from version control; add .env.example templates; ignore .claude local settings. Admin UI reads site gate from env only. Note: rotate secrets if repo history was ever public.

Made-with: Cursor

infogenie-backend-go/.gitignore

@@ -1,3 +1,4 @@
-# 含数据库密码、SMTP 等，勿提交
-.env.production
-.env.local
+# 含数据库密码、SMTP、JWT、Redis 等，勿提交
+.env
+.env.*
+!.env.example