Add open-source collaboration section to product README

Author: larai-w

README.md

@@ -6,6 +6,12 @@ Caregivers log daily bowel events and medication intake through a mobile-friendl
 
 **Status:** In development
 
+### Open-source collaboration
+
+- **Home Assistant** — **Merged** PR: [Accessible names for analytics consent switches](https://github.com/home-assistant/frontend/pull/54083)
+- **Microduck** — **In review** PR: [Fresh camera snapshots through robotctl and console HTTP](https://github.com/pollen-robotics/microduck/pull/241)
+- **stack-chan** — **In review** PR: [Deterministic sample sync for gallery output](https://github.com/stack-chan/stack-chan/pull/702)
+
 ---
 
 ## Why this exists