Fix Codex auth import and reset credit details

# Conflicts:
#	app/(tabs)/codex.tsx
#	app/(tabs)/index.tsx
#	app/(tabs)/settings.tsx
#	hooks/useCodexUsage.ts
#	lib/api/codexApi.ts
#	package-lock.json
#	package.json

app/onboarding/codex.tsx

@@ -8,6 +8,13 @@ import { saveCodexAuth, loadCodexAuth } from "@/lib/storage";
 import type { CodexAuth } from "@/types/codex";
 import { COLORS } from "@/lib/constants";
 
+function humanizeImportError(code: string): string {
+  if (code === "DOCUMENT_NOT_READABLE") {
+    return "The selected file could not be read. Try copying auth.json into Files or Downloads and import it again.";
+  }
+  return code;
+}
+
 export default function OnboardingCodexScreen() {
   const [auth, setAuth] = useState<CodexAuth | null>(null);
   const [loading, setLoading] = useState(false);
@@ -28,7 +35,7 @@ export default function OnboardingCodexScreen() {
       setAuth(parsed);
     } catch (e: unknown) {
       const msg = e instanceof Error ? e.message : "UNKNOWN_ERROR";
-      if (msg !== "PICKER_CANCELLED") setError(msg);
+      if (msg !== "PICKER_CANCELLED") setError(humanizeImportError(msg));
     } finally {
       setLoading(false);
     }
@@ -86,7 +93,7 @@ export default function OnboardingCodexScreen() {
                 <MaterialIcons name="check-circle" size={22} color={COLORS.codex} />
               </View>
               <View className="flex-1">
-                <Text className="text-white font-semibold">Connected</Text>
+                <Text className="text-white font-semibold">Imported</Text>
                 {auth.accountId && (
                   <Text className="text-neutral-500 text-sm font-mono">
                     {auth.accountId.slice(0, 12)}…