feat(dto): enforce field length constraints across DTOs

Add `@MaxLength` validations to limit string field lengths in multiple DTOs, ensuring consistent data validation and integrity. Integrate `CreateApiKeyDto` in the API keys controller for improved type safety.

backend/src/reports/dto/create-report.dto.ts

@@ -1,4 +1,4 @@
-import { IsEnum, IsOptional, IsString, IsUUID } from "class-validator";
+import { IsEnum, IsOptional, IsString, IsUUID, MaxLength } from "class-validator";
 
 export enum ReportReason {
 	INAPPROPRIATE = "inappropriate",
@@ -21,5 +21,6 @@ export class CreateReportDto {
 
 	@IsOptional()
 	@IsString()
+	@MaxLength(1000)
 	description?: string;
 }