fix(mining): calculate remainingDistribution from actual distributed amount

- Changed from reading config.remainingDistribution to calculating:
  remainingDistribution = distributionPool - totalDistributed
- Ensures data consistency: remaining + distributed = total pool
- Added Math.max(0, ...) to prevent negative values

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/mining-service/src/api/controllers/mining.controller.ts

@@ -68,7 +68,8 @@ export class MiningController {
 
     // 计算挖矿进度（用实际已分配数量 / 分配池总量）
     const distributionPool = Number(config.distributionPool || 0);
-    const remainingDistribution = Number(config.remainingDistribution || 0);
+    // 剩余分配池 = 总池 - 实际已分配（保持数据一致性）
+    const remainingDistribution = Math.max(0, distributionPool - totalDistributedDecimal);
     const miningProgress = distributionPool > 0 ? (totalDistributedDecimal / distributionPool) * 100 : 0;
 
     // 计算剩余分钟数