账户: 修改密码接口 + 账户设置页

- 后端 POST /auth/password: 校验旧密码(argon2id)后重哈希更新
- 前端 /console/settings 账户设置页: 个人资料卡 + 修改密码表单

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

server/internal/api/router.go

@@ -63,6 +63,7 @@ func NewRouter(a *app.App, gw *proxy.Gateway) *gin.Engine {
 			auth.POST("/login", h.Login)
 			auth.POST("/refresh", h.Refresh)
 			auth.POST("/logout", h.Logout)
+			auth.POST("/password", middleware.SessionAuth(a), h.ChangePassword)
 			auth.GET("/me", middleware.SessionAuth(a), h.Me)
 		}