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

client-app/components/ui/Avatar.tsx

@@ -0,0 +1,37 @@
+import React from 'react';
+import { View, Text } from 'react-native';
+import { cn } from '@/lib/utils';
+
+/** Deterministic color from a string */
+function colorFor(str: string): string {
+  const colors = [
+    'bg-blue-600', 'bg-purple-600', 'bg-green-600',
+    'bg-pink-600',  'bg-orange-600', 'bg-teal-600',
+    'bg-red-600',   'bg-indigo-600', 'bg-cyan-600',
+  ];
+  let h = 0;
+  for (let i = 0; i < str.length; i++) h = (h * 31 + str.charCodeAt(i)) >>> 0;
+  return colors[h % colors.length];
+}
+
+interface AvatarProps {
+  name?:      string;
+  size?:      'sm' | 'md' | 'lg';
+  className?: string;
+}
+
+const sizeMap = {
+  sm: { outer: 'w-8 h-8',   text: 'text-sm'  },
+  md: { outer: 'w-10 h-10', text: 'text-base' },
+  lg: { outer: 'w-14 h-14', text: 'text-xl'  },
+};
+
+export function Avatar({ name = '?', size = 'md', className }: AvatarProps) {
+  const initials = name.slice(0, 2).toUpperCase();
+  const { outer, text } = sizeMap[size];
+  return (
+    <View className={cn(outer, colorFor(name), 'rounded-full items-center justify-center', className)}>
+      <Text className={cn(text, 'text-white font-bold')}>{initials}</Text>
+    </View>
+  );
+}