refactor(modules): mark DatabaseModule and CryptoModule as global and remove redundant imports

Optimize module imports by marking `DatabaseModule` and `CryptoModule` as global. Remove explicit imports from other modules to reduce duplication and improve maintainability. Update environment variable limits for image and GIF sizes in production.

backend/src/database/database.module.ts

@@ -1,7 +1,8 @@
-import { Module } from "@nestjs/common";
+import { Global, Module } from "@nestjs/common";
 import { ConfigModule } from "@nestjs/config";
 import { DatabaseService } from "./database.service";
 
+@Global()
 @Module({
 	imports: [ConfigModule],
 	providers: [DatabaseService],