Phase 0: Remove plan operation limit fields (credit-only system)

- Removed all operation limit fields from Plan model
- Kept account management limits (max_users, max_sites, etc.)
- Updated PlanSerializer to remove limit fields
- Updated PlanAdmin to remove limit fieldsets
- Created migration to remove limit fields from database
- Plan model now only has credits, billing, and account management fields

backend/igny8_core/auth/models.py

@@ -93,8 +93,8 @@ class Account(models.Model):
 
 class Plan(models.Model):
     """
-    Subscription plan model with comprehensive limits and features.
-    Plans define limits for users, sites, content generation, AI usage, and billing.
+    Subscription plan model - Phase 0: Credit-only system.
+    Plans define credits, billing, and account management limits only.
     """
     BILLING_CYCLE_CHOICES = [
         ('monthly', 'Monthly'),
@@ -110,7 +110,7 @@ class Plan(models.Model):
     is_active = models.BooleanField(default=True)
     created_at = models.DateTimeField(auto_now_add=True)
     
-    # User / Site / Scope Limits
+    # Account Management Limits (kept - not operation limits)
     max_users = models.IntegerField(default=1, validators=[MinValueValidator(1)], help_text="Total users allowed per account")
     max_sites = models.IntegerField(
         default=1,
@@ -120,32 +120,7 @@ class Plan(models.Model):
     max_industries = models.IntegerField(default=None, null=True, blank=True, validators=[MinValueValidator(1)], help_text="Optional limit for industries/sectors")
     max_author_profiles = models.IntegerField(default=5, validators=[MinValueValidator(0)], help_text="Limit for saved writing styles")
     
-    # Planner Limits
-    max_keywords = models.IntegerField(default=1000, validators=[MinValueValidator(0)], help_text="Total keywords allowed (global limit)")
-    max_clusters = models.IntegerField(default=100, validators=[MinValueValidator(0)], help_text="Total clusters allowed (global)")
-    max_content_ideas = models.IntegerField(default=300, validators=[MinValueValidator(0)], help_text="Total content ideas allowed (global limit)")
-    daily_cluster_limit = models.IntegerField(default=10, validators=[MinValueValidator(0)], help_text="Max clusters that can be created per day")
-    daily_keyword_import_limit = models.IntegerField(default=100, validators=[MinValueValidator(0)], help_text="SeedKeywords import limit per day")
-    monthly_cluster_ai_credits = models.IntegerField(default=50, validators=[MinValueValidator(0)], help_text="AI credits allocated for clustering")
-    
-    # Writer Limits
-    daily_content_tasks = models.IntegerField(default=10, validators=[MinValueValidator(0)], help_text="Max number of content tasks (blogs) per day")
-    daily_ai_requests = models.IntegerField(default=50, validators=[MinValueValidator(0)], help_text="Total AI executions (content + idea + image) allowed per day")
-    monthly_word_count_limit = models.IntegerField(default=50000, validators=[MinValueValidator(0)], help_text="Monthly word limit (for generated content)")
-    monthly_content_ai_credits = models.IntegerField(default=200, validators=[MinValueValidator(0)], help_text="AI credit pool for content generation")
-    
-    # Image Generation Limits
-    monthly_image_count = models.IntegerField(default=100, validators=[MinValueValidator(0)], help_text="Max images per month")
-    daily_image_generation_limit = models.IntegerField(default=25, validators=[MinValueValidator(0)], help_text="Max images that can be generated per day")
-    monthly_image_ai_credits = models.IntegerField(default=100, validators=[MinValueValidator(0)], help_text="AI credit pool for image generation")
-    max_images_per_task = models.IntegerField(default=4, validators=[MinValueValidator(1)], help_text="Max images per content task")
-    image_model_choices = models.JSONField(default=list, blank=True, help_text="Allowed image models (e.g., ['dalle3', 'hidream'])")
-    
-    # AI Request Controls
-    daily_ai_request_limit = models.IntegerField(default=100, validators=[MinValueValidator(0)], help_text="Global daily AI request cap")
-    monthly_ai_credit_limit = models.IntegerField(default=500, validators=[MinValueValidator(0)], help_text="Unified credit ceiling per month (all AI functions)")
-    
-    # Billing & Add-ons
+    # Billing & Credits (Phase 0: Credit-only system)
     included_credits = models.IntegerField(default=0, validators=[MinValueValidator(0)], help_text="Monthly credits included")
     extra_credit_price = models.DecimalField(max_digits=10, decimal_places=2, default=0.01, help_text="Price per additional credit")
     allow_credit_topup = models.BooleanField(default=True, help_text="Can user purchase more credits?")