feat: Refactor rides app with unique constraints, mixins, and enhanced documentation

- Added migration to convert unique_together constraints to UniqueConstraint for RideModel.
- Introduced RideFormMixin for handling entity suggestions in ride forms.
- Created comprehensive code standards documentation outlining formatting, docstring requirements, complexity guidelines, and testing requirements.
- Established error handling guidelines with a structured exception hierarchy and best practices for API and view error handling.
- Documented view pattern guidelines, emphasizing the use of CBVs, FBVs, and ViewSets with examples.
- Implemented a benchmarking script for query performance analysis and optimization.
- Developed security documentation detailing measures, configurations, and a security checklist.
- Compiled a database optimization guide covering indexing strategies, query optimization patterns, and computed fields.

backend/apps/accounts/migrations/0013_add_user_query_indexes.py

@@ -0,0 +1,40 @@
+"""
+Add performance indexes and constraints to User model.
+
+This migration adds:
+1. db_index=True to is_banned and role fields for faster filtering
+2. Composite index on (is_banned, role) for common query patterns
+3. CheckConstraint to ensure banned users have a ban_date set
+"""
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('accounts', '0012_alter_toplist_category_and_more'),
+    ]
+
+    operations = [
+        # Add db_index to is_banned field
+        migrations.AlterField(
+            model_name='user',
+            name='is_banned',
+            field=models.BooleanField(default=False, db_index=True),
+        ),
+        # Add composite index for common query patterns
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(fields=['is_banned', 'role'], name='accounts_user_banned_role_idx'),
+        ),
+        # Add CheckConstraint for ban consistency
+        migrations.AddConstraint(
+            model_name='user',
+            constraint=models.CheckConstraint(
+                name='user_ban_consistency',
+                check=models.Q(is_banned=False) | models.Q(ban_date__isnull=False),
+                violation_error_message='Banned users must have a ban_date set'
+            ),
+        ),
+    ]