Comprehensive refactoring across 70 files (net -298 lines) improving
type safety, error handling, and code organization:
- Replace .passthrough()/.catchall(z.unknown()) with .strip() in all Zod schemas
- Tighten Record<string, unknown> to bounded union types where possible
- Replace throw new Error with domain-specific exceptions (OrderException,
FulfillmentException, WhmcsOperationException, SalesforceOperationException, etc.)
- Split AuthTokenService (625 lines) into TokenGeneratorService and
TokenRefreshService with thin orchestrator
- Deduplicate FreebitClientService with shared makeRequest() method
- Add typed interfaces to WHMCS facade, order service, and fulfillment mapper
- Externalize hardcoded config values to ConfigService with env fallbacks
- Consolidate duplicate billing cycle enums into shared billingCycleSchema
- Standardize logger usage (nestjs-pino @Inject(Logger) everywhere)
- Move shared WHMCS number coercion helpers to whmcs-utils/schema.ts
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