fix(security): harden jwt config and password rotation

src/types/index.ts

@@ -19,10 +19,6 @@ export interface Env {
 export type UserRole = 'admin' | 'user';
 export type UserStatus = 'active' | 'banned';
 
-// Sample JWT secret used by `.dev.vars.example`.
-// If runtime JWT_SECRET equals this value, treat it as unsafe.
-export const DEFAULT_DEV_SECRET = 'Enter-your-JWT-key-here-at-least-32-characters';
-
 // Attachment model
 export interface Attachment {
   id: string;