fix(rpc): run rescans and key imports without the 30 s timeout

A rescan or key import holds the node's cs_main for the whole wallet
scan. On the shared clients it hit the 30 s curl timeout, reported a
failure that wasn't one, abandoned a daemon RPC slot and flipped the app
into "node busy".

- One long wallet RPC at a time (rescan, importprivkey, importaddress,
  importwallet, z_importkey, z_importviewingkey, z_importwallet) runs on
  its own ungated client with no client timeout (rpc/long_call_lane.h).
  It can be aborted from any thread, and an abort is never lost, even
  one that lands before the client opens.
- The GUI rescan, key import and sweep use it. The sweep's fund-moving
  body is unchanged; only the client it calls differs. runtimeRescan()
  returns bool, and a refused post-bootstrap reconcile stays armed.
- The console routes rescan and the import commands through the lane;
  its input stays usable meanwhile, and a refusal is printed like any
  other result. RPCClient gains callRaw(.., timeoutSec).
- Restart, wallet switch, delete-chain, bootstrap (now also from
  Settings) and the other node-stopping flows are refused while it runs,
  with a message saying a key import or rescan is still running; quit
  asks for confirmation. The lane is aborted at quit.
- A second import or rescan is refused before the key is copied anywhere.
  An import cut off after the request reached the node (a lost reply,
  or a proxy's 502/504 while the node still imports) says the key may
  already be in the wallet and to run Settings -> Rescan. Only the
  node's own HTTP-layer refusals (401, 503, work queue full, unhandled
  request) say that the key was not imported. A pure
  classifyLongCallCutOff() makes that choice.
- New strings in all 8 languages; console results stay English.

Tests: the long-method list and the console's routing; one lane at a
time; an abort lands whether it comes before the client opens or during
the call; a call with no client timeout outlasts a 3 s scan, where a 1 s
gated client times out and marks the node busy; classifyLongCallCutOff()
for every failure kind with and without a sent request, and from raw
HTTP replies (502, 504, a plain 500 -> cut off; 401, 503, queue full,
unhandled -> refused).

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

res/lang/zh.json

@@ -86,6 +86,9 @@
     "appx_dragonxd_output": "dragonxd 输出",
     "appx_encrypting_wallet": "正在加密钱包…",
     "appx_fullnode_lifecycle_unavailable_lite": "全节点生命周期操作在轻量版中不可用",
+    "appx_import_cancelled": "已取消：节点可能仍在扫描。如果该密钥的资金没有显示，请运行“设置 → 重新扫描”。",
+    "appx_import_interrupted": "导入被中断，该密钥可能已在钱包中。如果其资金没有显示，请运行“设置 → 重新扫描”。",
+    "appx_import_refused": "节点拒绝了请求，因此未导入该密钥。",
     "appx_installing_bundled_daemon": "正在安装捆绑守护进程——节点将停止、更新并重启…",
     "appx_invalid_payment_uri_prefix": "无效的支付 URI：",
     "appx_ive_written_it_down": "我已抄写完毕",
@@ -134,6 +137,9 @@
     "appx_use_settings_restart_daemon_hint": "请使用 设置 > 重启守护进程 重试",
     "appx_waiting_for_daemon_to_encrypt_wallet": "正在等待守护进程加密钱包…",
     "appx_wallet_created_and_backed_up": "钱包已创建并完成备份。",
+    "appx_wallet_op_node_busy": "节点正忙，暂时无法响应。请在完成后重新导入或重新扫描。",
+    "appx_wallet_op_running": "密钥导入或重新扫描仍在进行中。请在完成后重试。",
+    "appx_wallet_op_shutting_down": "钱包正在关闭。",
     "appx_wallet_open_failed_prefix": "钱包打开失败：",
     "auto_shield": "自动屏蔽挖矿",
     "autoshield_by_node": "您的节点会自动为您屏蔽挖出的 coinbase。",
@@ -1944,6 +1950,8 @@
     "stopconfirm_rebuild_body": "已运行 %s，大型钱包可能需要约一小时。现在停止节点，要么会等待重建完成，要么下次启动时需要重新进行重建以及区块追赶。\n\n建议：关闭钱包并保持节点运行，它会自行完成。",
     "stopconfirm_rebuild_title": "节点正在重建票据见证",
     "stopconfirm_stop_wait": "停止节点并等待",
+    "stopconfirm_walletop_body": "节点正在为密钥导入或重新扫描扫描区块链。现在停止它会提前结束这次扫描，尚未扫描到的资金只有在“设置 → 重新扫描”之后才会显示。\n\n建议：关闭钱包并保持节点运行，它会自行完成扫描。",
+    "stopconfirm_walletop_title": "密钥导入或重新扫描正在进行",
     "stratum_allowip_hint": "允许来自指定 IP 或 CIDR 的矿工连接（留空 = 仅限本机）",
     "stratum_expose_warn": "会向您允许的网络开放挖矿端口——仅在受信任的局域网中使用。",
     "stratum_host": "托管矿池（stratum）",