fix: make the web bundle run and repair broken route declarations

- add babel.config.js with unstable_transformImportMeta: zustand/middleware ships
  import.meta.env, which the Metro web bundle (a classic script) cannot parse, so
  every page threw 'SyntaxError: Cannot use import.meta outside a module' and the
  app never hydrated after the static export.
- declare the settings screen as 'settings/index' in the root stack: the old name
  'settings' matched no route, so the modal presentation and the 'Settings' title
  were silently dropped (expo-router logged 'No route named settings exists').
- add the missing app/+not-found.tsx that the root layout already referenced.
- update the About label from LocalAiApp to LocalMind.

app/settings/index.tsx

@@ -215,7 +215,7 @@ export default function SettingsScreen() {
                 <View style={[styles.card, { backgroundColor: colors.cardBackground, borderColor: colors.border }]}>
                     <View style={styles.rowGroup}>
                         <Info size={18} color={colors.textMuted} style={styles.infoIcon} />
-                        <Text style={[styles.infoText, { color: colors.text }]}>LocalAiApp - Cross Platform Version</Text>
+                        <Text style={[styles.infoText, { color: colors.text }]}>LocalMind - Cross Platform Version</Text>
                     </View>
                     <View style={[styles.rowGroup, { marginTop: 8 }]}>
                         <MonitorCog size={18} color={colors.textMuted} style={styles.infoIcon} />