feat(client): 购买页三档 + 支付页 render_type 多态(crypto/redirect/qr 预留)+ 导航接线

购买页三档 pro(月/季/年,金额来自 GET /v1/pay/catalog)选档 → 选支付方式 → 下单;
支付页按 session.render_type 多态渲染(crypto_address 地址+精确金额+复制、redirect
外链拉起、qr 预留复制兜底),轮询用 Task 6 的 paymentFlowProvider,409
CURRENCY_MISMATCH 走「换方式开新单」。同时收口 paymentFlowProvider 非 autoDispose
带来的轮询生命周期缺口——支付页 dispose 时停轮询(cancel() 延后到微任务执行,避免
在自身 unmount 期间同步改 state 炸 Riverpod 断言)。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

client/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -11,6 +11,7 @@ import package_info_plus
 import screen_retriever_macos
 import shared_preferences_foundation
 import tray_manager
+import url_launcher_macos
 import window_manager
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
@@ -20,5 +21,6 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   ScreenRetrieverMacosPlugin.register(with: registry.registrar(forPlugin: "ScreenRetrieverMacosPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
   TrayManagerPlugin.register(with: registry.registrar(forPlugin: "TrayManagerPlugin"))
+  UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
   WindowManagerPlugin.register(with: registry.registrar(forPlugin: "WindowManagerPlugin"))
 }