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/app/(auth)/create.tsx

@@ -0,0 +1,82 @@
+/**
+ * Create Account screen.
+ * Generates a new Ed25519 + X25519 keypair and saves it securely.
+ */
+
+import React, { useState } from 'react';
+import { View, Text, ScrollView, Alert } from 'react-native';
+import { router } from 'expo-router';
+import { generateKeyFile } from '@/lib/crypto';
+import { saveKeyFile } from '@/lib/storage';
+import { useStore } from '@/lib/store';
+import { Button } from '@/components/ui/Button';
+import { Input } from '@/components/ui/Input';
+import { Card } from '@/components/ui/Card';
+
+export default function CreateAccountScreen() {
+  const setKeyFile = useStore(s => s.setKeyFile);
+  const [loading,  setLoading]  = useState(false);
+
+  async function handleCreate() {
+    setLoading(true);
+    try {
+      const kf = generateKeyFile();
+      await saveKeyFile(kf);
+      setKeyFile(kf);
+      router.replace('/(auth)/created');
+    } catch (e: any) {
+      Alert.alert('Error', e.message);
+    } finally {
+      setLoading(false);
+    }
+  }
+
+  return (
+    <ScrollView
+      className="flex-1 bg-background"
+      contentContainerClassName="px-6 pt-16 pb-10"
+    >
+      {/* Header */}
+      <Button variant="ghost" size="sm" onPress={() => router.back()} className="self-start mb-6 -ml-2">
+        ← Back
+      </Button>
+
+      <Text className="text-white text-3xl font-bold mb-2">Create Account</Text>
+      <Text className="text-muted text-base mb-8 leading-6">
+        A new identity will be generated on your device.
+        Your private key never leaves this app.
+      </Text>
+
+      {/* Info cards */}
+      <Card className="mb-4 gap-3">
+        <InfoRow icon="🔑" label="Ed25519 signing key" desc="Your blockchain address and tx signing key" />
+        <InfoRow icon="🔒" label="X25519 encryption key" desc="End-to-end encryption for messages" />
+        <InfoRow icon="📱" label="Stored on device" desc="Keys are encrypted in the device secure store" />
+      </Card>
+
+      <Card className="mb-8 border-primary/30 bg-primary/10">
+        <Text className="text-accent text-sm font-semibold mb-1">⚠ Important</Text>
+        <Text className="text-muted text-sm leading-5">
+          After creation, export and backup your key file.
+          If you lose it there is no recovery — the blockchain has no password reset.
+        </Text>
+      </Card>
+
+      <Button onPress={handleCreate} loading={loading} size="lg">
+        Generate Keys & Create Account
+      </Button>
+    </ScrollView>
+  );
+}
+
+function InfoRow({ icon, label, desc }: { icon: string; label: string; desc: string }) {
+  return (
+    <View className="flex-row items-start gap-3">
+      <Text className="text-xl">{icon}</Text>
+      <View className="flex-1">
+        <Text className="text-white text-sm font-semibold">{label}</Text>
+        <Text className="text-muted text-xs mt-0.5">{desc}</Text>
+      </View>
+    </View>
+  );
+}