feat: add user management system with roles and permissions

- Introduce SQLite persistence via GORM (stored at <data>/.ushare.db)
- Add Role model with two built-in roles: admin (all perms) and user (upload only)
- Add three permissions: user_manage, upload, token_manage (reserved)
- Rewrite UserManager: DB-backed login with in-memory session tokens
- Auto-seed default roles and admin user on first startup
- Add AuthPermission middleware for fine-grained permission checks
- Add /api/uauth/me endpoint for current session info
- Add /api/admin/* CRUD routes for user and role management
- Add admin console page (/admin) with user table and role permissions view
- Show admin console link in share page for users with user_manage permission

🤖 Generated with [Qoder][https://qoder.com]

internal/model/role.go

@@ -0,0 +1,44 @@
+package model
+
+import (
+	"strings"
+	"time"
+)
+
+const (
+	PermUserManage  = "user_manage"
+	PermUpload      = "upload"
+	PermTokenManage = "token_manage"
+
+	RoleAdmin = "admin"
+	RoleUser  = "user"
+)
+
+type Role struct {
+	ID          uint      `gorm:"primarykey" json:"id"`
+	Name        string    `gorm:"uniqueIndex;not null" json:"name"`
+	Label       string    `gorm:"not null" json:"label"`
+	Permissions string    `gorm:"not null" json:"permissions"`
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+func (r *Role) HasPermission(perm string) bool {
+	for _, p := range r.PermissionList() {
+		if p == perm {
+			return true
+		}
+	}
+	return false
+}
+
+func (r *Role) PermissionList() []string {
+	list := make([]string, 0)
+	for _, p := range strings.Split(r.Permissions, ",") {
+		p = strings.TrimSpace(p)
+		if p != "" {
+			list = append(list, p)
+		}
+	}
+	return list
+}

internal/model/user.go

@@ -1,10 +1,27 @@
 package model
 
+import "time"
+
+// User is the GORM database model for persistent user storage.
 type User struct {
-	Id       int    `json:"id"`
-	Username string `json:"username"`
-	Key      string `json:"key"`
-	Password string `json:"-"`
-	LoginAt  int64  `json:"login_at"`
-	Token    string `json:"token"`
+	ID        uint      `gorm:"primarykey" json:"id"`
+	Username  string    `gorm:"uniqueIndex;not null" json:"username"`
+	Password  string    `gorm:"not null" json:"-"`
+	RoleID    uint      `gorm:"not null" json:"role_id"`
+	Role      Role      `gorm:"foreignKey:RoleID" json:"role"`
+	Active    bool      `gorm:"default:true" json:"active"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// Session is the in-memory representation of an authenticated user.
+// It is created on login and stored in the UserManager session map.
+type Session struct {
+	UserID      uint     `json:"user_id"`
+	Username    string   `json:"username"`
+	Role        string   `json:"role"`
+	RoleLabel   string   `json:"role_label"`
+	Permissions []string `json:"permissions"`
+	LoginAt     int64    `json:"login_at"`
+	Token       string   `json:"token"`
 }