docs: add comprehensive potential issues analysis

Analyzed 7 potential areas of concern:
1. ⚠️ Sync tool performance in reactive streams
2. ⚠️ Complexity when mixing async/sync tools
3. ⚠️ Error handling consistency
4. ⚠️ Thread pool management
5. ⚠️ Test coverage gaps
6. ⚠️ Documentation completeness
7. ⚠️ Long-term backward compatibility

Priority Assessment:
- All issues are LOW to MEDIUM severity
- None are blockers for release
- Can be addressed in future iterations

Conclusion:
✅ Safe to release immediately
✅ Recommend follow-up improvements in v1.2.1

Related: #async-tool-support

Author: JGoP-L