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/(app)/_layout.tsx

@@ -1,127 +0,0 @@
-/**
- * Main app tab layout.
- * Redirects to welcome if no key found.
- */
-
-import React, { useEffect } from 'react';
-import { Tabs, router } from 'expo-router';
-import { Ionicons } from '@expo/vector-icons';
-import { useSafeAreaInsets } from 'react-native-safe-area-context';
-import { useStore } from '@/lib/store';
-import { useBalance } from '@/hooks/useBalance';
-import { useContacts } from '@/hooks/useContacts';
-import { useWellKnownContracts } from '@/hooks/useWellKnownContracts';
-import { getWSClient } from '@/lib/ws';
-
-const C_ACCENT = '#7db5ff';
-const C_MUTED  = '#98a7c2';
-const C_BG     = '#111a2b';
-const C_BORDER = '#1c2840';
-
-export default function AppLayout() {
-  const keyFile  = useStore(s => s.keyFile);
-  const requests = useStore(s => s.requests);
-  const insets   = useSafeAreaInsets();
-
-  useBalance();
-  useContacts();
-  useWellKnownContracts();  // auto-discover canonical system contracts from node
-
-  // Arm the WS client with this user's Ed25519 keypair. The client signs the
-  // server's auth nonce on every (re)connect so scoped subscriptions
-  // (addr:<my_pub>, inbox:<my_x25519>) are accepted. Without this the
-  // server would still accept global topic subs but reject scoped ones.
-  useEffect(() => {
-    const ws = getWSClient();
-    if (keyFile) {
-      ws.setAuthCreds({ pubKey: keyFile.pub_key, privKey: keyFile.priv_key });
-    } else {
-      ws.setAuthCreds(null);
-    }
-  }, [keyFile]);
-
-  useEffect(() => {
-    if (keyFile === null) {
-      const t = setTimeout(() => {
-        if (!useStore.getState().keyFile) router.replace('/');
-      }, 300);
-      return () => clearTimeout(t);
-    }
-  }, [keyFile]);
-
-  // Tab bar layout math:
-  //   icon (22) + gap (4) + label (~13) = ~39px of content
-  //   We add a 12px visual margin above, and pad the bottom by the larger of
-  //   the platform safe-area inset or 10px so the bar never sits flush on the
-  //   home indicator.
-  const BAR_CONTENT_HEIGHT = 52;
-  const bottomPad          = Math.max(insets.bottom, 10);
-
-  return (
-    <Tabs
-      screenOptions={{
-        headerShown:             false,
-        tabBarActiveTintColor:   C_ACCENT,
-        tabBarInactiveTintColor: C_MUTED,
-        tabBarLabelStyle: {
-          fontSize:    10,
-          fontWeight:  '500',
-          marginTop:   2,
-        },
-        tabBarStyle: {
-          backgroundColor: C_BG,
-          borderTopColor:  C_BORDER,
-          borderTopWidth:  1,
-          height:          BAR_CONTENT_HEIGHT + bottomPad,
-          paddingTop:      8,
-          paddingBottom:   bottomPad,
-        },
-      }}
-    >
-      <Tabs.Screen
-        name="chats"
-        options={{
-          tabBarLabel: 'Чаты',
-          tabBarIcon: ({ color, focused }) => (
-            <Ionicons
-              name={focused ? 'chatbubbles' : 'chatbubbles-outline'}
-              size={22}
-              color={color}
-            />
-          ),
-          tabBarBadge:      requests.length > 0 ? requests.length : undefined,
-          tabBarBadgeStyle: { backgroundColor: C_ACCENT, fontSize: 10 },
-        }}
-      />
-      <Tabs.Screen
-        name="wallet"
-        options={{
-          tabBarLabel: 'Кошелёк',
-          tabBarIcon: ({ color, focused }) => (
-            <Ionicons
-              name={focused ? 'wallet' : 'wallet-outline'}
-              size={22}
-              color={color}
-            />
-          ),
-        }}
-      />
-      <Tabs.Screen
-        name="settings"
-        options={{
-          tabBarLabel: 'Настройки',
-          tabBarIcon: ({ color, focused }) => (
-            <Ionicons
-              name={focused ? 'settings' : 'settings-outline'}
-              size={22}
-              color={color}
-            />
-          ),
-        }}
-      />
-      {/* Non-tab screens — hidden from tab bar */}
-      <Tabs.Screen name="requests"    options={{ href: null }} />
-      <Tabs.Screen name="new-contact" options={{ href: null }} />
-    </Tabs>
-  );
-}