feat(organisation): enable activity logging on Organisation model

Add spatie/laravel-activitylog LogsActivity trait tracking per-field
dirty changes on name, slug, contact_name, contact_email, phone, and
website. Log name "organisation", skip empty logs. Used by the dashboard
recent-activity feed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Models/Organisation.php

@@ -11,11 +11,14 @@ use Illuminate\Database\Eloquent\Relations\BelongsToMany;
 use Illuminate\Database\Eloquent\Relations\HasMany;
 use Illuminate\Database\Eloquent\Relations\HasOne;
 use Illuminate\Database\Eloquent\SoftDeletes;
+use Spatie\Activitylog\Models\Concerns\LogsActivity;
+use Spatie\Activitylog\Support\LogOptions;
 
 final class Organisation extends Model
 {
     use HasFactory;
     use HasUlids;
+    use LogsActivity;
     use SoftDeletes;
 
     protected $fillable = [
@@ -41,6 +44,15 @@ final class Organisation extends Model
         ];
     }
 
+    public function getActivitylogOptions(): LogOptions
+    {
+        return LogOptions::defaults()
+            ->logOnly(['name', 'slug', 'contact_name', 'contact_email', 'phone', 'website'])
+            ->logOnlyDirty()
+            ->dontLogEmptyChanges()
+            ->useLogName('organisation');
+    }
+
     public function users(): BelongsToMany
     {
         return $this->belongsToMany(User::class, 'organisation_user')