[Backend] — Test: `AchievementsService` TOTAL_STAKED achievements trigger at correct thresholds

[Olowodarey]

Background

AchievementsService.checkAndUnlockAchievements checks
AchievementType.TOTAL_STAKED_1M (1,000,000 stroops) and TOTAL_STAKED_10M
(10,000,000 stroops). There are no tests for these stake-based achievements
at their exact boundaries.

Goal

Add boundary tests in src/achievements/achievements.service.spec.ts.

Requirements

1. total_staked_stroops = '999999' (just below 1M) → TOTAL_STAKED_1M not
   unlocked.
2. total_staked_stroops = '1000000' (exactly 1M) → TOTAL_STAKED_1M unlocked.
3. total_staked_stroops = '9999999' (just below 10M) → TOTAL_STAKED_10M not
   unlocked; TOTAL_STAKED_1M already unlocked (mock it).
4. total_staked_stroops = '10000000' (exactly 10M) → both unlocked (only
   TOTAL_STAKED_10M awarded since 1M is pre-existing).

Acceptance criteria

• Achievements triggered at the exact boundary....

[gloskull]

Hello, I have 4 years of experience delivering solutions for projects like this, covering backend, frontend, and smart contract development. After carefully reviewing your requirements, I have a clear understanding of the task and am confident in my ability to deliver a clean, efficient, and thoroughly tested solution on time. I prioritize code quality, maintainability, and industry best practices throughout the development process.
My PR will be submitted in under 10hours.