fix: production readiness — resolve build, lint, and code quality issues

- Fix Next.js build failure: remove duplicate route at (dashboard)/listings/[id]
  that conflicted with (public)/listings/[id] (same URL path in two route groups)
- Fix 772 ESLint errors: auto-fix import ordering (import-x/order), remove unused
  imports/variables, convert empty interfaces to type aliases, replace require()
  with ESM imports, fix consistent-type-imports violations
- Add CLAUDE.md for developer onboarding documentation
- All checks pass: 0 lint errors, typecheck clean, 230 tests passing, build success

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/subscriptions/domain/__tests__/subscription.entity.spec.ts

@@ -1,7 +1,7 @@
 import { SubscriptionEntity } from '../entities/subscription.entity';
 
 describe('SubscriptionEntity', () => {
-  const makeSub = (overrides?: Partial<Parameters<typeof SubscriptionEntity.createNew>[0]>) => {
+  const makeSub = (_overrides?: Partial<Parameters<typeof SubscriptionEntity.createNew>[0]>) => {
     return SubscriptionEntity.createNew(
       'sub-1',
       'user-1',

apps/api/src/modules/subscriptions/domain/entities/subscription.entity.ts

@@ -1,11 +1,11 @@
-import { AggregateRoot } from '@modules/shared/domain/aggregate-root';
 import {
   type PlanTier,
   type SubscriptionStatus,
 } from '@prisma/client';
+import { AggregateRoot } from '@modules/shared/domain/aggregate-root';
+import { SubscriptionCancelledEvent } from '../events/subscription-cancelled.event';
 import { SubscriptionCreatedEvent } from '../events/subscription-created.event';
 import { SubscriptionUpgradedEvent } from '../events/subscription-upgraded.event';
-import { SubscriptionCancelledEvent } from '../events/subscription-cancelled.event';
 
 export interface SubscriptionProps {
   userId: string;

apps/api/src/modules/subscriptions/domain/events/subscription-cancelled.event.ts

@@ -1,5 +1,5 @@
-import { type DomainEvent } from '@modules/shared/domain/domain-event';
 import { type PlanTier } from '@prisma/client';
+import { type DomainEvent } from '@modules/shared/domain/domain-event';
 
 export class SubscriptionCancelledEvent implements DomainEvent {
   readonly eventName = 'subscription.cancelled';

apps/api/src/modules/subscriptions/domain/events/subscription-created.event.ts

@@ -1,5 +1,5 @@
-import { type DomainEvent } from '@modules/shared/domain/domain-event';
 import { type PlanTier } from '@prisma/client';
+import { type DomainEvent } from '@modules/shared/domain/domain-event';
 
 export class SubscriptionCreatedEvent implements DomainEvent {
   readonly eventName = 'subscription.created';

apps/api/src/modules/subscriptions/domain/events/subscription-upgraded.event.ts

@@ -1,5 +1,5 @@
-import { type DomainEvent } from '@modules/shared/domain/domain-event';
 import { type PlanTier } from '@prisma/client';
+import { type DomainEvent } from '@modules/shared/domain/domain-event';
 
 export class SubscriptionUpgradedEvent implements DomainEvent {
   readonly eventName = 'subscription.upgraded';