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

client-app/app/_layout.tsx

@@ -1,40 +0,0 @@
-import '../global.css';
-
-import React, { useEffect } from 'react';
-import { Stack } from 'expo-router';
-import { StatusBar } from 'expo-status-bar';
-import { View } from 'react-native';
-import { SafeAreaProvider } from 'react-native-safe-area-context';
-import { loadKeyFile, loadSettings } from '@/lib/storage';
-import { setNodeUrl } from '@/lib/api';
-import { useStore } from '@/lib/store';
-
-export default function RootLayout() {
-  const setKeyFile  = useStore(s => s.setKeyFile);
-  const setSettings = useStore(s => s.setSettings);
-
-  // Bootstrap: load key + settings from storage
-  useEffect(() => {
-    (async () => {
-      const [kf, settings] = await Promise.all([loadKeyFile(), loadSettings()]);
-      if (kf) setKeyFile(kf);
-      setSettings(settings);
-      setNodeUrl(settings.nodeUrl);
-    })();
-  }, []);
-
-  return (
-    <SafeAreaProvider>
-      <View className="flex-1 bg-background">
-        <StatusBar style="light" />
-        <Stack
-          screenOptions={{
-            headerShown:   false,
-            contentStyle:  { backgroundColor: '#0b1220' },
-            animation:     'slide_from_right',
-          }}
-        />
-      </View>
-    </SafeAreaProvider>
-  );
-}