fix(daemon): never restart, delete or swap under a node that hasn't exited

Every operation that stops the node (restart, rescan, repair, delete
chain data, reinstall, bootstrap, wallet switch/adopt/restore/rebuild,
wizard restart, encrypt, decrypt) now:

- refuses up front while the node is rebuilding witnesses or has not
  answered for 30s, with a "try again when it's done" warning, and sends
  no stop;
- goes ahead only once the node's PROCESS has exited, not its RPC port.
  A stop that doesn't finish within 120s cancels the operation (warning;
  a cancelled rescan/repair disarms its flags); nothing is started over
  the old node, chain data isn't deleted, wallet.dat isn't swapped.

Specifics:
- stopDaemonForWalletSwitch() no longer reports "stopped" when the app
  is quitting (adopt could swap wallet.dat under a live node).
- Decrypt waited a fixed 3s after "stop" before renaming wallet.dat; it
  now waits for the process to exit, and scrubs the key export if not.
- Bootstrap waits for the process before cleanChainData and stops the
  node through the stop routine instead of the shared RPC client.
- StopScope::Connected lets switch/reinstall/decrypt stop an adopted or
  external node through the same never-kill routine.
- A bounded stop that can't reach the node (a foreign node refusing our
  credentials) gives up after 5s instead of 120s.
- macOS: isDaemonProcessRunning() checks processes (libproc), not the
  RPC port.
- rpcBusyWhileAlive() also reads the busy gate: since the gate, the
  first timeout usually lands on another lane and the 30s clock never
  started (also weakened the quit prompt for a silent rebuild).
- Notifications render during the first-run wizard.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

res/lang/zh.json

@@ -100,6 +100,8 @@
     "appx_no_bundled_daemon_to_install": "此版本没有可安装的捆绑守护进程",
     "appx_no_embedded_daemon_to_install": "此版本没有可安装的内嵌守护进程",
     "appx_node_busy_restarting": "节点正忙于重启——请稍后再试。",
+    "appx_node_busy_try_later": "节点正忙于完成一项耗时任务（例如重建票据见证）。请在完成后重试；现在停止它可能导致这项工作从头开始。",
+    "appx_node_not_stopped": "节点未能及时停止，因此未做任何更改。请几分钟后重试。",
     "appx_not_next_word": "  — 这不是下一个词",
     "appx_payment_request_loaded": "支付请求已加载",
     "appx_pool_miner_connected_and_hashing": "矿池矿工已连接并正在计算哈希。",