feat(api): onboarding API (MS22-P1e) (#612)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/onboarding/onboarding.guard.ts

@@ -0,0 +1,17 @@
+import { CanActivate, ExecutionContext, ForbiddenException, Injectable } from "@nestjs/common";
+import { OnboardingService } from "./onboarding.service";
+
+@Injectable()
+export class OnboardingGuard implements CanActivate {
+  constructor(private readonly onboardingService: OnboardingService) {}
+
+  async canActivate(_context: ExecutionContext): Promise<boolean> {
+    const completed = await this.onboardingService.isCompleted();
+
+    if (completed) {
+      throw new ForbiddenException("Onboarding already completed");
+    }
+
+    return true;
+  }
+}