feat: Implement user-branch relationship and update user management views

- Added a many-to-many relationship between users and branches in User model.
- Updated user creation and editing views to support multiple branch selection.
- Modified user index view to display associated branches.
- Created UserBranch model to manage user-branch associations.
- Added migration for user_branches table with foreign key constraints.
- Implemented seeder to populate user_branches based on existing user branch data.

Run this command:
- php artisan migrate
- php artisan module:seed Usermanagement --class=UserBranchesSeeder

app/Models/User.php

@@ -73,8 +73,8 @@ class User extends Authenticatable
     {
         return [
             'email_verified_at' => 'datetime',
-            'password'          => 'hashed',
-            'id'                => 'string',
+            'password' => 'hashed',
+            'id' => 'string',
         ];
     }
 
@@ -107,4 +107,9 @@ class User extends Authenticatable
     {
         return $this->hasMany(Appointment::class, 'admin_id');
     }
+
+    public function branches()
+    {
+        return $this->belongsToMany(Branch::class, 'user_branches', 'user_id', 'branch_id');
+    }
 }