docs: add docs folder (architecture, developer, usage); update README; wire probe TTL cache + concurrency notes into docs

README.md

@@ -4,10 +4,12 @@
 - Rust services (Cargo workspace): `aggregate/`, `gateway/`, `projection/`, `runner/`, `control/api/`, `shared/`
 - Control UI: `control/ui/`
 - Docker + Swarm + Compose: `docker/`, `docker-compose.yml`, `swarm/`, `observability/`
-- Transport plans:
-  - `TRANSPORT_DEVELOPMENT_PLAN.md`
-  - `GATEWAY_TRANSPORT_PLAN.md`
-  - `NATS_TRANSPORT_PLAN.md`
+
+## Documentation
+- docs/README.md
+- Architecture: docs/architecture/overview.md, docs/architecture/transport.md
+- Developer: docs/developer/setup.md, docs/developer/testing.md
+- Usage: docs/usage/quickstart.md, docs/usage/api.md, docs/usage/nats.md
 
 ## Quick Start (Docker Compose)
 
@@ -35,4 +37,5 @@ More details: `DOCKER.md`
 cargo fmt --check
 cargo clippy --workspace --all-targets -- -D warnings
 cargo test --workspace
+cd control/ui && npm ci && npm run lint && npm run typecheck && npm run test && npm run build
 ```