Add project documentation and update workflow plan

Adds AGENTS.md, DESIGN.md, and docs/* covering architecture,
conventions, decisions, checklists, branching, release process,
and prompts. Updates README and workflow-feedback-plan to reflect
the decoupled GroupName nomination model.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -13,10 +13,25 @@ Production monorepo for the VTuber Star Awards platform.
 - `frontend/` Vue application and public assets
 - `Backend/` ASP.NET Core API, EF Core migrations, services and endpoints
 - `.gitea/workflows/ci.yaml` build, hygiene, deploy and live verification pipeline
+- `docs/PROJECT.md` project facts, runtime expectations and documentation map
+- `docs/ARCHITECTURE.md` system structure, source-of-truth and deployment flow
+- `docs/CONVENTIONS.md` coding, validation, review and documentation standards
+- `docs/DECISIONS.md` durable architecture and operations decisions
 - `docker-compose.dev.yml` optional local PostgreSQL container for development
 
 Generated archives, prototype exports, Word handoff files and local document-update scripts are intentionally ignored and should not be committed.
 
+## Engineering Docs
+
+Start with:
+
+- [AGENTS.md](AGENTS.md) for the engineering execution contract.
+- [docs/PROJECT.md](docs/PROJECT.md) for project/runtime facts.
+- [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md) for system boundaries.
+- [docs/CONVENTIONS.md](docs/CONVENTIONS.md) for coding and validation standards.
+- [docs/CHECKLISTS.md](docs/CHECKLISTS.md) for quality gates.
+- [DESIGN.md](DESIGN.md) for UI and product design guidance.
+
 ## Local Development
 
 Start the database:
@@ -96,3 +111,6 @@ The pipeline:
 7. Verifies live health, database connectivity and frontend assets.
 
 Production runs at `https://award.noveria.net`.
+
+See [docs/release-process.md](docs/release-process.md) for release readiness,
+smoke tests and rollback expectations.