refactor(data): move Result utility to utils and simplify API

Relocate the Result type from `@/data/result` to `@/utils/result` and
replace the discriminated-union API (`kind`/`value`) with a simpler
boolean-based API (`success`/`data`) across all repositories and
storage classes for improved readability and consistency.

src/data/repositories/metrics_repository.ts

@@ -10,7 +10,7 @@
 import { MetricsApi, metricsApi } from "@/data/api";
 import { AppEvent } from "@/data/dto/metrics/app_event";
 import { PwaEvent } from "@/data/dto/metrics/pwa_event";
-import { Result } from "@/data/result";
+import { Result } from "@/utils/result";
 
 export class MetricsRepository {
   constructor(private readonly api: MetricsApi) {}