refactor: migrate frontend to React + Tailwind, add Docker + tests

Replace the vanilla-TS innerHTML frontend with a type-checked React
component tree (React 19 + Tailwind v4 + Vite).

Frontend:
- 14 components: Header, Stepper, LoginPage, LoginModal, SignPage,
  DropZone, DevicePicker, ProgressCard, SavedAccountsList, TrustModal,
  TwoFactorModal, Button, Field, Chip, Modal
- lib/ extracts: storage (10 localStorage keys preserved), pair-record,
  account-session, log-parser, ids, use-log hook
- flows/ encapsulate async pair/login/sign/install with dependency injection
- Accounts page as main view with Add Account modal
- Fullscreen progress overlay during sign/install
- Account selector + device picker on Sign page
- Security notice in login modal (server trust warning)
- All addLog calls mirrored to console.log for devtools debugging

Build:
- bun run dev: submodule init + install + wasm dist + vite + wrangler
- bun run setup: one-shot project bootstrap
- Docker: multi-stage bun build → nginx on :3000
- build:wasm:dist copies pre-built src→dist (no Rust/Emscripten needed)
- jszip/node-forge/fflate pre-bundled for CJS→ESM conversion

Tests:
- 163 vitest tests (happy-dom): all lib, components, App integration,
  WASM dist artifact checks, libcurl Apple connectivity, anisette init
  error handling

Cleanup:
- Delete yarn.lock (bun.lock canonical), expand .gitignore
- Remove README.zh.md, rewrite README.md + AGENTS.md
- Update libcurl.js submodule to f65d440 (CI build artifacts)

.gitignore

@@ -1,3 +1,40 @@
+# Dependencies
 node_modules/
-lib/
-.idea/
+.pnp/
+.pnp.js
+
+# Build outputs
+dist/
+build/
+out/
+*.tsbuildinfo
+# webmuxd package compiled output
+dependencies/webmuxd/lib/
+
+# Caches
+.cache/
+.turbo/
+.vite/
+.parcel-cache/
+
+# Editor / IDE
+.idea/
+.vscode/
+!.vscode/extensions.json
+*.swp
+*.swo
+.DS_Store
+
+# Logs + env
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+.env
+.env.local
+.env.*.local
+
+# Misc
+coverage/
+.wrangler/