refactor: migrate all internal imports to package.json subpath aliases

- Add #domain, #protocol, #utils aliases to package.json imports map
- Replace all relative imports (./, ../, ../..) in app/ and
  database/mongo_migrations/ with the corresponding #alias imports,
  eliminating relative path traversal across the codebase
- Remove dead code: ConfigurationVersionModel.findByConfigurationIdentifier
  (unused, superseded by paginateVersions) and unused exception classes
  (NotFoundException, UnprocessableEntityException, DatabaseException)
  from app/exceptions/index.ts, keeping only BadRequestException
- Fix pre-existing syntax error in configuration_version.ts (mismatched
  parenthesis) that broke tsc
- Fix eqeqeq violation in configuration_service.ts and isNaN ->
  Number.isNaN in configuration_engine.ts / cwmp-1-0.ts / exchange_controller.ts
- Fix no-shadow violation in cwmp-1-0.ts EventStruct constructor
- Prettier formatting pass on touched files

Validated: tsc --noEmit clean, eslint app/ clean, full test suite green.

app/protocol/common/cwmp_message_builder.ts

@@ -21,20 +21,20 @@ import {
   SetParameterValues,
   TransferCompleteResponse,
   Upload,
-} from '../cwmp-1-0.js'
+} from '#protocol/cwmp-1-0'
 import {
   CwmpID,
   NAMESPACES,
   SoapEnvelope,
   type SoapEnvelopeAttribute,
   SoapEnvelopeHeader,
-} from '../soap_envelope.js'
+} from '#protocol/soap_envelope'
 import type {
   DownloadTaskPayload,
   UploadTaskPayload,
   SetParameterValuesTaskPayload,
   SetParameterAttributesTaskPayload,
-} from '../tr069_types.js'
+} from '#protocol/tr069_types'
 
 function generateCwmpID(): string {
   return randomBytes(4).toString('hex')