fix(planting): 无推荐人时分享权益进入分享权益池

- 将无推荐人时的分享权益目标从 SYSTEM_HEADQUARTERS_COMMUNITY 改为 SYSTEM_SHARE_RIGHT_POOL
- 将 SYSTEM:OPERATION_ACCOUNT 改为 SYSTEM:SHARE_RIGHT_POOL

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/services/planting-service/src/domain/services/fund-allocation.service.ts

@@ -96,6 +96,7 @@ export class FundAllocationDomainService {
     );
 
     // 4. 分享权益: 500 USDT/棵 (分配给推荐链)
+    // 无推荐人时进入分享权益池 SYSTEM_SHARE_RIGHT_POOL
     allocations.push(
       new FundAllocation(
         FundAllocationTargetType.REFERRAL_RIGHTS,
@@ -103,7 +104,7 @@ export class FundAllocationDomainService {
           treeCount,
         context.referralChain.length > 0
           ? context.referralChain[0]
-          : 'SYSTEM_HEADQUARTERS_COMMUNITY',
+          : 'SYSTEM_SHARE_RIGHT_POOL',
         { referralChain: context.referralChain },
       ),
     );
@@ -228,10 +229,10 @@ export class FundAllocationDomainService {
     );
 
     // 4. 分享权益 (直推奖励): 500 USDT/棵
-    // 仅直推，无多级；无推荐人归入运营账户
+    // 仅直推，无多级；无推荐人归入分享权益池
     const referralTarget = context.directReferrerId
       ? `USER:${context.directReferrerId}`
-      : 'SYSTEM:OPERATION_ACCOUNT';
+      : 'SYSTEM:SHARE_RIGHT_POOL';
     allocations.push(
       new FundAllocation(
         FundAllocationTargetType.REFERRAL_RIGHTS,