refactor: fix all lint errors and reduce warnings across BFF and domain
Eliminate all 12 ESLint errors (nested ternaries, any types) and reduce
warnings by 13 (duplicate strings, complexity). Key changes:
- Domain: extract helpers for nested ternaries in opportunity/contract and whmcs/mapper
- BFF core: fix any type in safe-operation.util, refactor exception filter to use
options objects, create shared CACHE_CONTROL and normalizeToArray utilities
- Freebit: replace nested ternaries with if/else in client and mapper services
- Sim fulfillment: extract helper methods to reduce complexity (fulfillEsim,
fulfillPhysicalSim, buildMnpPayload, registerVoiceOptionsIfAvailable, MNP_FIELD_MAPPINGS)
- Modules: fix 8 nested ternary violations across validators, services, controllers
- Constants: extract duplicate strings (CSRF, email, orchestrator, cache control)