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/migrations/0014_remove_plan_operation_limits_phase0.py

@@ -0,0 +1,86 @@
+# Generated manually for Phase 0: Remove plan operation limit fields (credit-only system)
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('igny8_core_auth', '0013_remove_ai_cost_per_request'),
+    ]
+
+    operations = [
+        # Remove Planner Limits
+        migrations.RemoveField(
+            model_name='plan',
+            name='max_keywords',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='max_clusters',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='max_content_ideas',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_cluster_limit',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_keyword_import_limit',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_cluster_ai_credits',
+        ),
+        # Remove Writer Limits
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_content_tasks',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_ai_requests',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_word_count_limit',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_content_ai_credits',
+        ),
+        # Remove Image Generation Limits
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_image_count',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_image_generation_limit',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_image_ai_credits',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='max_images_per_task',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='image_model_choices',
+        ),
+        # Remove AI Request Controls
+        migrations.RemoveField(
+            model_name='plan',
+            name='daily_ai_request_limit',
+        ),
+        migrations.RemoveField(
+            model_name='plan',
+            name='monthly_ai_credit_limit',
+        ),
+    ]
+