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

node/swagger_assets.go

@@ -0,0 +1,32 @@
+package node
+
+import (
+	_ "embed"
+	"net/http"
+)
+
+//go:embed swagger/openapi.json
+var swaggerOpenAPI string
+
+//go:embed swagger/index.html
+var swaggerIndexHTML string
+
+func registerSwaggerRoutes(mux *http.ServeMux) {
+	mux.HandleFunc("/swagger/openapi.json", serveSwaggerOpenAPI)
+	mux.HandleFunc("/swagger", serveSwaggerUI)
+	mux.HandleFunc("/swagger/", serveSwaggerUI)
+}
+
+func serveSwaggerOpenAPI(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	_, _ = w.Write([]byte(swaggerOpenAPI))
+}
+
+func serveSwaggerUI(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/swagger" && r.URL.Path != "/swagger/" {
+		http.NotFound(w, r)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	_, _ = w.Write([]byte(swaggerIndexHTML))
+}