Pivot Data and Eager Loading: Efficient Many-to-Many Queries

Sometimes pivot tables store extra data:
- assigned_at
- created_by
- quantity

    ## Add pivot fields
    
    ```php
    public function tags() {
      return $this->belongsToMany(Tag::class)
        ->withPivot('assigned_at')
        ->withTimestamps();
    }
    ```
    
    ## Avoid N+1 with eager loading
    
    ```php
    $posts = Post::with('tags')->latest()->get();
    ```
    
    ## Graph: query count control
    
    ```mermaid
    flowchart TD
      A[Load Posts] --> B[Load Tags in bulk]
      B --> C[Render UI]
    ```
    
    In the next tutorial, we will use database constraints to enforce data integrity.