chore: migrate to pnpm workspaces monorepo with Turborepo

- Restructure directories: apps/api, apps/admin, apps/website
- Add root pnpm-workspace.yaml, turbo.json, .prettierrc, .gitignore
- Rename packages to @inkreach/api, @inkreach/admin, @inkreach/website
- Add shared packages: packages/tsconfig, packages/shared-types
- Add pnpm.onlyBuiltDependencies for native builds
- Update docs: README.md, structs.md
- All three projects build successfully

apps/api/src/common/interceptors/transform.interceptor.ts

@@ -0,0 +1,19 @@
+import {
+  CallHandler,
+  ExecutionContext,
+  Injectable,
+  NestInterceptor,
+} from '@nestjs/common';
+import { Observable, map } from 'rxjs';
+
+/**
+ * Wraps every successful response into `{ data, success: true }`.
+ *
+ * Exceptions still flow through the global filter and are not wrapped.
+ */
+@Injectable()
+export class TransformInterceptor implements NestInterceptor {
+  intercept(_context: ExecutionContext, next: CallHandler): Observable<unknown> {
+    return next.handle().pipe(map((data) => ({ data, success: true })));
+  }
+}