feat: RPC node failover system + accessibility fixes for modals

.env.example

@@ -1,5 +1,8 @@
-# Steem RPC node(s). Comma-separated for failover (e.g. https://api.steemit.com,https://api.steem.fans)
-STEEM_RPC_URL=https://api.steemit.com
+# Steem RPC node(s). Comma-separated for failover (tried left-to-right on error).
+STEEM_RPC_URL=https://api.steem.fans,https://api2.justyy.com,https://api.steemit.com,https://api.moecki.online,https://steem.senior.workers.dev,https://steemd.steemworld.org
+
+# Predefined RPC nodes shown in the UI node-selector (comma-separated).
+NEXT_PUBLIC_RPC_NODES=https://api.steem.fans,https://api2.justyy.com,https://api.steemit.com,https://api.moecki.online,https://steem.senior.workers.dev,https://steemd.steemworld.org
 
 # Session and CSRF secrets (generate strong values in production)
 # SESSION_SECRET=your-session-secret-here

CLAUDE.md

@@ -0,0 +1,85 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Commands
+
+```bash
+pnpm dev              # Start Next.js dev server (localhost:3000)
+pnpm build            # Production build
+pnpm lint             # ESLint
+pnpm type-check       # TypeScript check (tsc --noEmit)
+pnpm test             # Run unit tests (Vitest)
+pnpm test:coverage    # Unit tests with coverage report
+pnpm e2e              # Playwright E2E tests (requires dev server)
+pnpm e2e:ui           # Playwright UI mode
+```
+
+Run a single unit test file:
+```bash
+pnpm vitest run tests/unit/auth-slice.test.ts
+```
+
+## Architecture
+
+**Steem blockchain wallet** built on Next.js 16 App Router. Users authenticate with a Steem username and private key; private keys never leave the browser.
+
+### Request flow
+
+1. Browser → Next.js API routes (`src/app/api/`) for all blockchain operations
+2. API routes apply CSRF + rate-limit middleware before calling `SteemService`
+3. Broadcast transactions: client signs via `SteemSigner` (client-side) → posts signed tx to `/api/broadcast/*`
+4. Queries: browser calls `/api/query/*` → server-side `SteemService` connects to RPC nodes with failover
+
+### Key separation: client vs server Steem code
+
+- [src/lib/steem/client.ts](src/lib/steem/client.ts) — `SteemSigner` (key-based tx signing, browser only) + `apiClient` helper
+- [src/lib/steem/server.ts](src/lib/steem/server.ts) — `SteemService` (queries + broadcast, server only, multi-node failover)
+
+### State management
+
+Redux Toolkit with three slices in [src/lib/store/slices/](src/lib/store/slices/):
+- `auth` — username, private keys, isAuthenticated, challenge
+- `wallet` — balances and account history
+- `ui` — theme, open modals
+
+Private keys are stored in Redux but excluded from serialization checks via custom middleware.
+
+### Routing
+
+Next.js App Router with locale prefix: `src/app/[locale]/`. Locales: `en`, `zh`, `es` (default: `en`) via next-intl. Translation files live in [src/i18n/messages/](src/i18n/messages/).
+
+Dynamic route `[locale]/[username]/` renders the wallet dashboard for a given Steem account. Modal state (open transfer/delegate forms etc.) is encoded in URL search params via [src/lib/wallet/wallet-modal-search-params.ts](src/lib/wallet/wallet-modal-search-params.ts).
+
+### API routes
+
+All under `src/app/api/`:
+- `auth/` — login challenge, session creation/destruction
+- `broadcast/` — transfer, delegate, power-down, witness vote, convert SBD, withdraw routes
+- `query/` — account data, history, global properties, price feed, witness list
+- `analytics/` — Mixpanel event forwarding
+- `health/` — health check
+
+### Middleware
+
+[src/lib/middleware/](src/lib/middleware/) is applied in API route handlers (not Next.js `middleware.ts`):
+- `csrf.ts` — verifies CSRF token on mutating requests
+- `rate-limit.ts` — separate in-memory buckets for `query`, `broadcast`, and `auth` endpoints
+
+### Testing
+
+- **Unit tests**: Vitest + jsdom, files in `tests/unit/`. External libs (`@steemit/steem-js`, `mixpanel-browser`) are aliased to mocks in `tests/mocks/`.
+- **E2E tests**: Playwright (Chromium only), files in `tests/e2e/`. Playwright auto-starts the dev server.
+- Coverage thresholds: 80% lines/functions/statements, 60% branches.
+
+### UI
+
+shadcn/ui components (Radix Nova style) in [src/components/ui/](src/components/ui/). Wallet-specific forms and display components live in [src/components/wallet/](src/components/wallet/). Tailwind CSS 4 for all styling.
+
+### Environment variables
+
+See `.env.example`. Key vars: `STEEM_RPC_URL`, `SESSION_SECRET`, `CSRF_SECRET`, `NEXT_PUBLIC_MIXPANEL_TOKEN`, `NEXT_PUBLIC_SIGNUP_URL`.
+
+### CI
+
+GitHub Actions (`.github/workflows/ci.yml`) runs on push to `master` and `next`: type-check → lint → unit tests + coverage → build → E2E.