Support multiple named wallets per app install in both demos

[jamaljsr]

Summary

The demos used to hard-bind one wallet per browser origin or device install: one dataDir, one passkey marker, and a network dropdown that silently rewired the same wallet between networks. This reworks both demo apps (web and React Native) around a wallet registry, so one install can hold many wallets side by side.

The user-facing shape, identical in both demos:

• First run shows a create form: wallet name, a network picker (signet, testnet, regtest behind a dev gate), and for regtest an advanced endpoints section. The network is chosen once, at creation, and bound to the wallet permanently; there is no post-create network switcher.
• Returning users land on a wallet list (name, network chip, unlock-kind icon, last used) and pick a wallet to reach its unlock screen. Switching wallets is stop-then-start on the single runtime; nothing runs concurrently.
• Settings gains the wallet identity (name, network, created date) with switch and delete actions; the old "wipe everything" affordance survives as an explicit "Clear all data" on the list footer.
• A wallet that predates the registry migrates automatically into it and asks for its network once, on first open, keeping its passkey or password identity.

This is demo-layer only: no packages/* source changes, no new SDK surface. The registry is localStorage on web and AsyncStorage on React Native, deliberately app-local, since wallet bookkeeping is a host-app concern the SDK does not prescribe.

Technical Notes

• One runtime, sequential wallets. The daemon is a per-origin/per-process singleton (wasm Web Lock on web, gomobile package singleton on RN), so the registry model is sequential switching, not concurrency. True multi-profile concurrency remains the leader-tab follow-up tracked from Fail fast with wallet_locked when the wallet is open in another tab #56.
• Per-wallet isolation by dataDir. Every new wallet gets its own /wallets/<id> (web OPFS) or <defaultRoot>/<id> (RN) directory. A migrated legacy wallet keeps the bare default root it already lives in, which is why deletion guards below exist.
• Deletion semantics differ by platform, deliberately. Web removal is list-only (OPFS stores flat, hash-named files, so surgical per-wallet deletion is not safely expressible); RN removal really deletes the wallet's directory via expo-file-system. On both, a legacy root-dwelling entry skips the disk wipe so it can never take sibling wallets' data with it, and the confirm copy states the exception.
• Network permanence over convenience. The picker binds at creation because the daemon's on-disk stores are per-network; rewiring a live dataDir across networks is exactly the foot-gun the old dropdown invited. Legacy entries record their network only after a successful unlock proves the guess, and a wrong guess loops back to the picker instead of poisoning the entry.
• Restores stamp late. The registry marks a wallet's unlock kind only once the restored wallet is actually up, so a restore that dies before then re-renders the restore form with the preserved failure instead of the "data missing" screen.
• Dev gates. Regtest is hidden behind ?regtest=1 on web and a long-press on the brand mark on RN, keeping the hosted-network demo path clean.
• RN has no hermetic rig. The web changes are covered by the Playwright suite (extended from 5 to 8 scenarios: multi-wallet identity separation, legacy migration, removal/first-run restore). The RN half ships a manual verification checklist in the demo README; there is no mock target for a compiled-in native runtime.

Steps to Test

CI covers build, typecheck, and the unit suites. The end-to-end checks:

Web (hermetic, no regtest stack needed):

1. WAVELENGTH_DIR="$(cd ../wavelength && pwd)" pnpm --filter web-wallet-demo run wasm:local
2. pnpm --filter web-wallet-demo run build
3. pnpm --filter web-wallet-demo run test - exercises create, two-wallet switching, legacy migration, removal, and the data-missing recovery path.

React Native (manual, device-driven):

1. pnpm --filter @lightninglabs/wavelength-react-native run fetch-bindings
2. cd apps/rn-wallet-demo && npx expo run:android
3. Walk the "Multi-wallet manual verification" checklist at the end of the demo README.

Related Issues & Pull Requests

Depends on:

• Nothing. react-native: fetch prebuilt bindings from the pinned release #62 (release-download bindings staging) already merged; this branch is rebased on it.

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.