chore: initial commit for v0.0.1

DChain single-node blockchain + React Native messenger client.

Core:
- PBFT consensus with multi-sig validator admission + equivocation slashing
- BadgerDB + schema migration scaffold (CurrentSchemaVersion=0)
- libp2p gossipsub (tx/v1, blocks/v1, relay/v1, version/v1)
- Native Go contracts (username_registry) alongside WASM (wazero)
- WebSocket gateway with topic-based fanout + Ed25519-nonce auth
- Relay mailbox with NaCl envelope encryption (X25519 + Ed25519)
- Prometheus /metrics, per-IP rate limit, body-size cap

Deployment:
- Single-node compose (deploy/single/) with Caddy TLS + optional Prometheus
- 3-node dev compose (docker-compose.yml) with mocked internet topology
- 3-validator prod compose (deploy/prod/) for federation
- Auto-update from Gitea via /api/update-check + systemd timer
- Build-time version injection (ldflags → node --version)
- UI / Swagger toggle flags (DCHAIN_DISABLE_UI, DCHAIN_DISABLE_SWAGGER)

Client (client-app/):
- Expo / React Native / NativeWind
- E2E NaCl encryption, typing indicator, contact requests
- Auto-discovery of canonical contracts, chain_id aware, WS reconnect on node switch

Documentation:
- README.md, CHANGELOG.md, CONTEXT.md
- deploy/single/README.md with 6 operator scenarios
- deploy/UPDATE_STRATEGY.md with 4-layer forward-compat design
- docs/contracts/*.md per contract

.gitignore

@@ -0,0 +1,58 @@
+# Build output
+/bin/
+/node.exe
+/client.exe
+/peerid.exe
+/wallet.exe
+*.test
+*.out
+
+# Local state from running node/relay directly (NOT in docker)
+/chaindata/
+/mailboxdata/
+/node.json
+/relay.json
+/seeds.json
+
+# Go tool caches
+.gobin/
+.gocache/
+.golangci-cache/
+.gomodcache/
+.gopath/
+
+# IDE / editor
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# Docker compose local overrides
+docker-compose.override.yml
+
+# Prod deploy secrets (operators must generate their own; never commit)
+/deploy/prod/keys/
+/deploy/prod/node*.env
+!/deploy/prod/node.env.example
+/deploy/single/keys/
+/deploy/single/node.env
+!/deploy/single/node.env.example
+# Single-node update marker written by update.sh
+/deploy/single/.last-update
+
+# Node modules (client-app has its own .gitignore too, this is belt+braces)
+node_modules/
+
+# Expo / React Native
+.expo/
+*.log
+dist/
+web-build/
+
+# macOS / Windows cruft
+.DS_Store
+Thumbs.db
+
+# Claude Code / agent local state
+.claude/