Enforce doc-first protocol, add SGen, modular plugin docs
- Enforced strict documentation-first AI agent protocol in `.github/copilot-instructions.md` (multi-repo, no auto doc edits, explicit consent, [LOADED_DOCS] prefix, [DOCUMENTATION CHECK] on code changes)
- Updated solution structure: added `docs` folder to solution items for LLM/AI context
- Integrated AyCode SGen (source-generated binary serialization) with forced runtime registration; documented SGen usage and exclusions
- Overhauled plugin `README.md` and added modular docs: `SCHEMA.md`, `DOMAIN_MODEL.md`, `MEASUREMENT.md`, `DATA_LAYER.md`, `AI_SERVICES.md`, `SIGNALR_ENDPOINTS.md`
- Updated `CLAUDE.md` to require reading copilot instructions first
- Switched appsettings connection string to production DB
- Minor doc clarifications, corrects, and project file updates
Loretta
3725b4c2fd