管理员默认密码 admin/admin，首次登录强制改密码；增加服务器部署配置

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/backend/internal/router/router.go

@@ -26,6 +26,7 @@ func New(d *handlers.Deps, mgr *auth.Manager, authStore *store.AuthStore, dist f
 
 			r.Post("/logout", d.Logout)
 			r.Get("/me", d.Me)
+			r.Post("/change-password", d.ChangePassword)
 			r.Get("/scores", d.ListScores)
 			r.Get("/scores/{id}", d.GetScore)
 			r.Get("/contracts", d.ListContracts)