fix: resolve all lint errors across codebase

- Convert CacheTTL enum to const object to fix duplicate value errors
- Fix import ordering in test files (eslint-disable for vi.mock pattern)
- Fix unused variable warnings (prefix with underscore)
- Auto-fix import ordering in subscription page, dashboard layout
- 0 lint errors remaining

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

apps/api/src/modules/shared/infrastructure/cache.service.ts

@@ -7,22 +7,22 @@ import { type RedisService } from './redis.service';
 export const CACHE_HIT_TOTAL = 'cache_hit_total';
 export const CACHE_MISS_TOTAL = 'cache_miss_total';
 
-export enum CacheTTL {
+export const CacheTTL = {
   /** Listing detail — moderate TTL, invalidated on mutation */
-  LISTING_DETAIL = 300, // 5 min
+  LISTING_DETAIL: 300, // 5 min
   /** Search results — short TTL due to high variability */
-  SEARCH_RESULTS = 60, // 1 min
+  SEARCH_RESULTS: 60, // 1 min
   /** District stats — moderate TTL, invalidated on listing events */
-  DISTRICT_STATS = 300, // 5 min
+  DISTRICT_STATS: 300, // 5 min
   /** Market report — moderate TTL, invalidated on listing events */
-  MARKET_REPORT = 900, // 15 min
+  MARKET_REPORT: 900, // 15 min
   /** Heatmap data — moderate TTL, invalidated on listing events */
-  HEATMAP = 300, // 5 min
+  HEATMAP: 300, // 5 min
   /** Price trend — long TTL, historical data changes infrequently */
-  MARKET_DATA = 1800, // 30 min
+  MARKET_DATA: 1800, // 30 min
   /** User profile — moderate TTL, invalidated on mutation */
-  USER_PROFILE = 600, // 10 min
-}
+  USER_PROFILE: 600, // 10 min
+} as const;
 
 export enum CachePrefix {
   LISTING = 'cache:listing',