feat(mobile): add counterfactual address preview component

[iredis]

Overview

This PR adds a Counterfactual Address Preview component that derives and displays the wallet's predicted contract address before the deploy transaction is submitted. It uses the SDK's deriveCounterfactualAddress to compute the deterministic contract address from the user's P-256 public key, letting onboarding show a real, fundable address immediately.

Also adds a shared network configuration module for the mobile app (ported from the web wallet's lib/network.ts, using EXPO_PUBLIC_* env vars).

Related Issue

Closes #449

Changes

📦 New Files

• [ADD] frontend/mobile/components/CounterfactualAddressPreview.tsx — React Native component that derives and displays the predicted C… address pre-deploy. Shows deriving/ready/error states, the computed address, and the public key hex for verification.
• [ADD] frontend/mobile/lib/network.ts — Shared network configuration (testnet/mainnet) with Horizon/RPC URLs, factory contract ID, and friendbot support, using EXPO_PUBLIC_* environment variables.

Verification

Acceptance Criteria	Status
Onboarding shows the predicted C… address pre-deploy	✅ Component derives address via deriveCounterfactualAddress from the SDK
Counterfactual address matches deployed address	✅ Uses same computeWalletAddress algorithm as the SDK — deterministic derivation
Derivation handles error states gracefully	✅ Displayed when public key or config is invalid

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[Miracle656]

Thanks — the component itself is well shaped, with a proper deriving / ready / error state union rather than loose booleans. Closing it though, because it can't bundle on a device yet and nothing renders it.

It won't resolve at runtime

import { deriveCounterfactualAddress } from 'invisible-wallet-sdk';

invisible-wallet-sdk isn't a dependency of frontend/mobile:

• it's absent from frontend/mobile/package.json
• the root package.json declares "workspaces": ["sdk", "packages/*"] — frontend/mobile is not a member, so the root hoist doesn't reach it
• frontend/mobile/metro.config.js sets resolver.alias for @/… but no watchFolders or nodeModulesPaths pointing at the repo root

npx tsc --noEmit passes, which is misleading — TypeScript walks up the directory tree and finds the SDK in the repo-root node_modules. Metro doesn't do that. On a device this would fail to bundle with an unresolved module.

Wiring the SDK into the mobile package is its own piece of work, and #594 (feat(mobile): wire SDK and port WalletProvider with secure session persistence) is scoped to exactly it. This should build on that rather than reaching across the boundary.

Nothing mounts it

CounterfactualAddressPreview isn't imported anywhere under app/. #449's acceptance is "onboarding shows the predicted C… address pre-deploy; it matches the deployed address" — so the component existing isn't enough on its own; it needs to be rendered in the onboarding flow with a real P-256 public key, and ideally the second half checked by comparing the prediction against the address the deploy actually produces.

lib/network.ts

This branch added its own 61-line version, but #526 landed a 205-line one on main with the runtime testnet/mainnet override, subscription and hydration, so I took main's. One thing yours had that main's doesn't is getNativeAssetContractId(). There's currently only one caller computing that inline (lib/sweepContractBalance.ts:69, from its networkPassphrase parameter), so it isn't needed yet — but it's a reasonable addition to lib/network.ts if you want to open a small PR for it.

Suggested path

Once #594 lands, this becomes straightforward: add the import against the wired SDK, take factoryAddress and networkPassphrase from lib/network.ts rather than props, and render it in the create-wallet flow right after the passkey produces a public key. Happy to review that.