feat(server): implement switchable logging formats (console/json) (#24791)

* feat(server): add LogFormat enum and configuration

* feat(server): add structured logging formatters

* feat(server): implement switchable logging formats (console/json)

* Revert "feat(server): add LogFormat enum and configuration"

This reverts commit 565e95ae68.

* feat(server): implement JSON logging using NestJS native support

* refactor: rename LOG_FORMAT to IMMICH_LOG_FORMAT for consistency

* docs: add IMMICH_LOG_FORMAT documentation

* chore: format environment-variables.md

* chore: format monitoring.md

server/src/enum.ts

@@ -454,6 +454,11 @@ export enum LogLevel {
   Fatal = 'fatal',
 }
 
+export enum LogFormat {
+  Console = 'console',
+  Json = 'json',
+}
+
 export enum ApiCustomExtension {
   Permission = 'x-immich-permission',
   AdminOnly = 'x-immich-admin-only',