feat: 自适应并发调度 — 网络探测 + AIMD + 参数智能推导

扫描前自动探测网络环境（RTT、丢包率、fd limit），基于探测数据
推导 6 个关键参数，替代硬编码默认值：

- Timeout: median_RTT + 4σ（覆盖 99.9% 正常连接）
- ModuleThreadNum: target_concurrency / 30
- MaxRetries: ceil(log(0.01)/log(loss_rate))（全失败概率 <1%）
- ICMPRate: 环境基准 × fd 系数
- PocNum: 跟随 ModuleThreadNum
- DisablePing: 已有 ICMP 权限降级机制

线程池从单信号（资源耗尽率）升级为 AIMD + 慢启动：
- 慢启动：target/4 起步，500ms 翻倍
- 稳态 AIMD：健康 +5%，拥塞 ×0.5
- 双信号：资源耗尽率 + RTT 趋势（双 EMA）

用户 -t 显式指定时作为 ceiling，探测仍调整其他参数。

测试：单元 + 边界 + 集成 + 真实网络，core 包 580+ 用例全通过。

common/i18n/locales/en.yaml

@@ -541,6 +541,26 @@ icmp_debug_stable_done:
   other: "[ICMP] response stable, ending early, elapsed {{.Arg1}}, alive {{.Arg2}}/{{.Arg3}}"
 adaptive_pool_resource_exhausted:
   other: "[AdaptivePool] resource exhaustion rate {{.Arg1}}%, threads {{.Arg2}} -> {{.Arg3}}"
+adaptive_pool_decrease:
+  other: "Concurrency adjusted: {{.Arg1}} -> {{.Arg2}} (pressure detected)"
+adaptive_pool_increase:
+  other: "Concurrency adjusted: {{.Arg1}} -> {{.Arg2}} (network healthy)"
+adaptive_pool_slowstart_exit:
+  other: "Slow start exit: current {{.Arg1}} (congestion detected)"
+net_probe_result:
+  other: "Network probe: {{.Arg1}}, RTT {{.Arg2}}ms, loss {{.Arg3}}%, concurrency {{.Arg4}}/{{.Arg5}}"
+net_env_lan:
+  other: "LAN"
+net_env_wan:
+  other: "WAN"
+net_env_internet:
+  other: "Internet"
+net_env_slow:
+  other: "Slow network"
+env_tune_summary:
+  other: "Adaptive params: Timeout={{.Arg1}}ms, ModuleThread={{.Arg2}}, Retry={{.Arg3}}, ICMPRate={{.Arg4}}, PocNum={{.Arg5}}"
+env_fd_limit:
+  other: "fd limit constraint: threads {{.Arg1}} -> {{.Arg2}} (ulimit={{.Arg3}})"
 
 # ========================= Service Plugin Messages =========================
 # Format: {service}_{type} - type: credential/unauth/service/vuln