feat: add Usage Limits Panel component with usage tracking and visual indicators for limits

style: implement custom color schemes and gradients for account section, enhancing visual hierarchy

backend/igny8_core/business/billing/models.py

@@ -189,6 +189,83 @@ class CreditCostConfig(models.Model):
         super().save(*args, **kwargs)
 
 
+class PlanLimitUsage(AccountBaseModel):
+    """
+    Track monthly usage of plan limits (ideas, words, images, prompts)
+    Resets at start of each billing period
+    """
+    LIMIT_TYPE_CHOICES = [
+        ('content_ideas', 'Content Ideas'),
+        ('content_words', 'Content Words'),
+        ('images_basic', 'Basic Images'),
+        ('images_premium', 'Premium Images'),
+        ('image_prompts', 'Image Prompts'),
+    ]
+    
+    limit_type = models.CharField(
+        max_length=50,
+        choices=LIMIT_TYPE_CHOICES,
+        db_index=True,
+        help_text="Type of limit being tracked"
+    )
+    amount_used = models.IntegerField(
+        default=0,
+        validators=[MinValueValidator(0)],
+        help_text="Amount used in current period"
+    )
+    
+    # Billing period tracking
+    period_start = models.DateField(
+        help_text="Start date of billing period"
+    )
+    period_end = models.DateField(
+        help_text="End date of billing period"
+    )
+    
+    # Metadata
+    metadata = models.JSONField(
+        default=dict,
+        blank=True,
+        help_text="Additional tracking data (e.g., breakdown by site)"
+    )
+    
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+    
+    class Meta:
+        app_label = 'billing'
+        db_table = 'igny8_plan_limit_usage'
+        verbose_name = 'Plan Limit Usage'
+        verbose_name_plural = 'Plan Limit Usage Records'
+        unique_together = [['account', 'limit_type', 'period_start']]
+        ordering = ['-period_start', 'limit_type']
+        indexes = [
+            models.Index(fields=['account', 'limit_type']),
+            models.Index(fields=['account', 'period_start', 'period_end']),
+            models.Index(fields=['limit_type', 'period_start']),
+        ]
+    
+    def __str__(self):
+        account = getattr(self, 'account', None)
+        return f"{account.name if account else 'No Account'} - {self.get_limit_type_display()} - {self.amount_used} used"
+    
+    def is_current_period(self):
+        """Check if this record is for the current billing period"""
+        from django.utils import timezone
+        today = timezone.now().date()
+        return self.period_start <= today <= self.period_end
+    
+    def remaining_allowance(self, plan_limit):
+        """Calculate remaining allowance"""
+        return max(0, plan_limit - self.amount_used)
+    
+    def percentage_used(self, plan_limit):
+        """Calculate percentage of limit used"""
+        if plan_limit == 0:
+            return 0
+        return min(100, int((self.amount_used / plan_limit) * 100))
+
+
 class Invoice(AccountBaseModel):
     """
     Invoice for subscription or credit purchases