Address issues from Sean Wu (see google doc)

[smitdave]

• semi-Markov discussion: add to the agenda
• Modify Figure2.drawio to include observed PR & mean logged parasite counts

https://docs.google.com/document/d/1_D8hzxB6dfgRtHbsL3xVhFgFvnUnz7oh5KbGy2XU-OA/edit?tab=t.0