docs: add Six Sigma Agent, AgileCoder, Reflexion citations to taxonomy paper

Incorporate findings from literature survey: Six Sigma Agent (arXiv:2601.22290)
as the only prior explicit PM/OM-named framework, AgileCoder for Scrum sprints,
Reflexion as implicit PDCA, CAMEL for role theory.

paper/taxonomy-refs.bib

@@ -40,6 +40,56 @@
   url={https://github.com/XORwell/archeflow}
 }
 
+@article{nguyen2024agilecoder,
+  title={AgileCoder: Dynamic Collaborative Agents for Software Development based on Agile Methodology},
+  author={Nguyen, Minh Huynh and Chau, Thang Phan and Phung, Phong X. and Nguyen, Nghi D. Q.},
+  journal={arXiv preprint arXiv:2406.11912},
+  year={2024},
+  url={https://arxiv.org/abs/2406.11912}
+}
+
+@article{patel2026sixsigma,
+  title={The Six Sigma Agent: Achieving Enterprise-Grade Reliability in LLM Systems Through Consensus-Driven Decomposed Execution},
+  author={Patel, Rushi and Surendira, Bala and George, Allen and Kapale, Kiran},
+  journal={arXiv preprint arXiv:2601.22290},
+  year={2026},
+  url={https://arxiv.org/abs/2601.22290}
+}
+
+@article{shinn2023reflexion,
+  title={Reflexion: Language Agents with Verbal Reinforcement Learning},
+  author={Shinn, Noah and Cassano, Federico and Gopinath, Ashwin and Narasimhan, Karthik and Yao, Shunyu},
+  journal={Advances in Neural Information Processing Systems},
+  volume={36},
+  year={2023},
+  url={https://arxiv.org/abs/2303.11366}
+}
+
+@article{xia2024eddops,
+  title={Evaluation-Driven Development and Operations of LLM Agents: A Process Model and Reference Architecture},
+  author={Xia, Boming and Lu, Qinghua and Zhu, Liming and Xing, Zhenchang and Zhao, Dehai and Zhang, Hao},
+  journal={arXiv preprint arXiv:2411.13768},
+  year={2024},
+  url={https://arxiv.org/abs/2411.13768}
+}
+
+@article{rasheed2024survey,
+  title={LLM-Based Multi-Agent Systems for Software Engineering: Literature Review, Vision and the Road Ahead},
+  author={Rasheed, Zeeshan and others},
+  journal={ACM Transactions on Software Engineering and Methodology},
+  year={2025},
+  url={https://arxiv.org/abs/2404.04834}
+}
+
+@article{li2023camel,
+  title={CAMEL: Communicative Agents for ``Mind'' Exploration of Large Language Model Society},
+  author={Li, Guohao and Hammoud, Hasan Abed Al Kader and Itani, Hani and Khizbullin, Dmitrii and Ghanem, Bernard},
+  journal={Advances in Neural Information Processing Systems},
+  volume={36},
+  year={2023},
+  url={https://arxiv.org/abs/2303.17760}
+}
+
 % ---- Persona Stability ----
 
 @article{lu2026assistant,