Stage 0: scaffold monorepo, backend skeleton, docs, CI

- go.work (Go 1.26.3) with backend module; deps added incrementally (gin+zap only)

- backend: /healthz + /readyz, env config, graceful shutdown

- docs: ARCHITECTURE, FUNCTIONAL (+ru mirror), TESTING

- PLAN.md (stage tracker + per-stage open details) and CLAUDE.md (per-stage workflow)

- .gitea go-unit CI (gofmt/vet/build/test)

README.md

@@ -0,0 +1,45 @@
+# scrabble-game
+
+Multiplatform Scrabble game. Players arrive from a platform (Telegram first;
+later VK/MAX/iOS/Android) or from standalone web (email / guest). The game
+supports English Scrabble, Russian Scrabble and Эрудит.
+
+## Components
+
+- **`gateway`** — the only public ingress: anti-abuse, platform authentication
+  (resolves the player and injects `X-User-ID`), routing to `backend`, and an
+  admin surface behind Basic Auth. *(added in a later stage)*
+- **`backend`** — internal-only service that owns every domain concern and
+  embeds the [`scrabble-solver`](../scrabble-solver) engine library in-process.
+- **`ui`** — pure-HTML5 client (plain Svelte + Vite), embeddable in platform
+  webviews and packageable to native via Capacitor. *(added in a later stage)*
+- **`platform/*`** — per-platform side-services (e.g. the Telegram bot).
+  *(added in a later stage)*
+
+## Documentation (sources of truth)
+
+- [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) — global architecture, transport,
+  security, cross-service contracts.
+- [`docs/FUNCTIONAL.md`](docs/FUNCTIONAL.md) (+ [`_ru`](docs/FUNCTIONAL_ru.md)) —
+  per-domain user stories.
+- [`docs/TESTING.md`](docs/TESTING.md) — test layers and the per-stage CI gate.
+- [`PLAN.md`](PLAN.md) — the staged implementation plan and stage tracker.
+- [`CLAUDE.md`](CLAUDE.md) — project guide and the mandatory per-stage workflow.
+
+## Build & test
+
+```sh
+go build ./backend/...  # per module (the workspace spans several modules)
+go vet ./backend/...
+gofmt -l .              # must print nothing
+go test -count=1 ./backend/...
+```
+
+## Run the backend locally
+
+```sh
+go run ./backend/cmd/backend     # serves /healthz and /readyz on :8080
+```
+
+Configuration is read from the environment: `BACKEND_HTTP_ADDR` (default
+`:8080`), `BACKEND_LOG_LEVEL` (`debug|info|warn|error`, default `info`).