chore(release): clean up repo for v0.0.1 release

Excluded from release bundle:
- CONTEXT.md, CHANGELOG.md (agent/project working notes)
- client-app/ (React Native messenger — tracked separately)
- contracts/hello_go/ (unused standalone example)

Kept contracts/counter/ and contracts/name_registry/ as vm-test fixtures
(referenced by vm/vm_test.go; NOT production contracts).

Docs refactor:
- docs/README.md — new top-level index with cross-references
- docs/quickstart.md — rewrite around single-node as primary path
- docs/node/README.md — full rewrite, all CLI flags, schema table
- docs/api/README.md — add /api/well-known-version, /api/update-check
- docs/contracts/README.md — split native (Go) vs WASM (user-deployable)
- docs/update-system.md — new, full 5-layer update system design
- README.md — link into docs/, drop CHANGELOG/client-app references

Build-time version system (inherited from earlier commits this branch):
- node --version / client --version with ldflags-injected metadata
- /api/well-known-version with {build, protocol_version, features[]}
- Peer-version gossip on dchain/version/v1
- /api/update-check against Gitea release API
- deploy/single/update.sh with semver guard + 15-min systemd jitter

docs/README.md

@@ -0,0 +1,34 @@
+# DChain documentation
+
+Справочник по блокчейн-ноде DChain. Читается в любом порядке, но если в первый
+раз — идите по разделам сверху вниз.
+
+## Оглавление
+
+| Документ | О чём |
+|----------|-------|
+| [quickstart.md](quickstart.md) | Поднять ноду локально за 5 минут |
+| [architecture.md](architecture.md) | 4 слоя стека: network / chain / transport / app |
+| [node/README.md](node/README.md) | Запуск ноды (docker, native, deployment) |
+| [update-system.md](update-system.md) | Версионирование, `/api/update-check`, auto-update от Gitea |
+| [api/README.md](api/README.md) | REST + WebSocket API endpoints |
+| [cli/README.md](cli/README.md) | CLI `client` — команды, флаги, примеры |
+| [contracts/README.md](contracts/README.md) | Системные контракты (native + WASM) |
+| [development/README.md](development/README.md) | SDK для написания своих контрактов (TinyGo) |
+| [node/governance.md](node/governance.md) | On-chain governance, голосование параметров |
+| [node/multi-server.md](node/multi-server.md) | Multi-validator federation deploy |
+
+## Внешние ссылки из репо
+
+- [README.md](../README.md) — обзор проекта
+- [deploy/single/README.md](../deploy/single/README.md) — operator runbook для single-node
+- [deploy/prod/README.md](../deploy/prod/README.md) — operator runbook для multi-validator
+- [deploy/UPDATE_STRATEGY.md](../deploy/UPDATE_STRATEGY.md) — дизайн forward-compat обновлений (4 слоя)
+
+## Соглашения
+
+- **Единицы:** микро-токены (`µT`). 1 T = 1,000,000 µT. MinFee = 1000 µT = 0.001 T.
+- **Pubkey:** 32-байтный Ed25519 (hex, 64 символа).
+- **Address:** `DC` + первые 24 hex-символа SHA-256(pubkey).
+- **ChainID:** `dchain-` + первые 12 hex-символов SHA-256 genesis-блока.
+- **Времена:** RFC 3339 (UTC) везде, кроме internal-счётчиков в Prometheus (unix seconds).