Documentation & Knowledge Base

**Greatly improve technical and onboarding documentation.**

Tasks:
- [ ] Fill gaps in proof management and protocol docs
- [ ] Expand developer/contributor guides
- [ ] Structure docs per component (server, mobile, beacon, robot)
- [ ] Update security and refactoring notes across all modules

[See README & REFACTORING_PLAN](https://github.com/indoor-mall-nav/navign/blob/main/README.md#support)
