fix(plugins): 出站主机授权两处真缺陷 —— 已启动 worker 看不到新授权、授权不落盘

生产实证：channels 插件的 auth/state 在主机已授权后仍被拒
（auth/state 失败: host "copilot.tencent.com" is not an allowed outbound destination），
而 /api/plugins/channels/kernel 明明显示 hosts_granted=26。

缺陷一（授权对已启动 worker 无效）：
  httpAllowlist 是不可变快照；bootPluginState 在 worker 启动时把指针绑进 Lua
  闭包，闭包与 worker 同寿。GrantExtraHosts 之后 ps.allowHTTP 被**整个换新**
  （newHTTPAllowlist 返回新实例），已启动的 worker 仍持旧指针 → 授权接口返回
  ok、设置页显示已批，请求却继续被拒。分片 VM（plugin_shard.go）同样中招。
  修法：allowlist 改为带 RWMutex 的**可变共享对象**，GrantExtraHosts 与
  rebuildOutboundAllowlistLocked 原地 add —— 所有闭包立即看到新授权，worker
  无需重建。rebuild 从"替换实例"改为"原地折叠"，并在注释里写明为什么。

缺陷二（授权不持久化）：
  .kernel-perms.json 只写 actions；hosts 授权只存在运行态 map，重启即失。
  设置页看不出异常（actions 有持久化，读起来像"都持久化了"）。
  修法：文件行改为 jsonPluginPolicy{actions,all_read,hosts}（旧文件向后兼容，
  纯 actions 行照常解析）；Load 恢复 extraHosts；Save 把每个插件的 host 授权
  与 actions 一起写入（支持"只批了主机、没批动作"的行）。

回归测试（internal/lua/plugin_http_test.go）：
- TestGrantExtraHostsVisibleToAlreadyBootedWorker：按事故顺序构造（先启动
  worker → 再授权），断言同一批 worker 立即可用新授权 + 旧引用不再失效。
- TestHostGrantsPersistAcrossRestart：授权落盘 + 新 registry 读回 + 插件重载
  后授权保留。

go test ./internal/lua/ 全绿；build/vet 通过。

internal/lua/kernel_perms_persist.go

@@ -45,7 +45,12 @@ func (ps *Plugins) LoadKernelPermissions() error {
 	if err != nil {
 		return err
 	}
-	raw := map[string]jsonPermission{}
+	// The file holds BOTH kernel-action grants (map[string]jsonPermission, the
+	// historical shape) AND, for plugins that asked for them, the operator's
+	// extra-host grants (map[string]jsonPluginPolicy.Hosts). A bare
+	// {actions:[...]} row still parses into jsonPluginPolicy with empty Hosts,
+	// so old files load unchanged.
+	raw := map[string]jsonPluginPolicy{}
 	if err := json.Unmarshal(b, &raw); err != nil {
 		return err
 	}
@@ -54,8 +59,17 @@ func (ps *Plugins) LoadKernelPermissions() error {
 	if ps.kernelPerms == nil {
 		ps.kernelPerms = kernelPermissionSet{}
 	}
+	if ps.extraHosts == nil {
+		ps.extraHosts = map[string][]string{}
+	}
 	for name, jp := range raw {
-		ps.kernelPerms[name] = jp.unmarshal()
+		ps.kernelPerms[name] = KernelPermission{Actions: jp.Actions, AllRead: jp.AllRead}
+		if len(jp.Hosts) > 0 {
+			// Load the persisted grant into extraHosts WITHOUT folding it into the
+			// allowlist yet — sources are loaded later, and the caller owns that
+			// fold. GrantExtraHosts rebuilds the allowlist when sources are ready.
+			ps.extraHosts[name] = append([]string(nil), jp.Hosts...)
+		}
 	}
 	return nil
 }
@@ -65,12 +79,17 @@ func (ps *Plugins) LoadKernelPermissions() error {
 // Grants drop unknown action names on write. If an operator authorized an action
 // that a later release removed, keeping the name would leave a stale entry that
 // nothing can ever satisfy — and it would reappear in the UI as if it were live.
+//
+// Host grants travel in the same file (jsonPluginPolicy.Hosts): a granted host is
+// the operator's explicit decision to let a plugin egress somewhere, and losing
+// it across a restart (the previous behaviour) made grants silently vanish.
 func (ps *Plugins) saveKernelPermissionsLocked() {
 	path := ps.kernelPermsFile()
 	if path == "" {
 		return
 	}
-	out := map[string]jsonPermission{}
+	out := map[string]jsonPluginPolicy{}
+	something := false
 	for name, perm := range ps.kernelPerms {
 		valid := make([]string, 0, len(perm.Actions))
 		for _, a := range perm.Actions {
@@ -78,12 +97,28 @@ func (ps *Plugins) saveKernelPermissionsLocked() {
 				valid = append(valid, a)
 			}
 		}
-		if len(valid) == 0 && !perm.AllRead {
+		row := policyFromActions(KernelPermission{Actions: valid, AllRead: perm.AllRead})
+		if hs := ps.extraHosts[name]; len(hs) > 0 {
+			row.Hosts = append([]string(nil), hs...)
+		}
+		if len(valid) == 0 && !perm.AllRead && len(row.Hosts) == 0 {
 			continue // nothing granted: presence would be a lie
 		}
-		out[name] = KernelPermission{Actions: valid, AllRead: perm.AllRead}.marshal()
+		out[name] = row
+		something = true
 	}
-	if len(out) == 0 {
+	// A plugin may hold host grants with NO kernel actions granted (operators
+	// approve hosts and actions independently). Emit those too.
+	for name, hs := range ps.extraHosts {
+		if len(hs) == 0 {
+			continue
+		}
+		if _, exists := out[name]; !exists {
+			out[name] = jsonPluginPolicy{Hosts: append([]string(nil), hs...)}
+			something = true
+		}
+	}
+	if !something {
 		_ = os.Remove(path)
 		return
 	}