后端与全仓代码质量清理（golangci 扩展集 · 测试质量 · 并发安全 · 文档同步）

代码质量全量清理，零行为变化：golangci 扩展集 13 类 linter（gosec/modernize/perfsprint/canonicalheader/usestdlibvars/wastedassign/intrange/errorlint/forcetypeassert/recvcheck/exhaustive/unparam）全量修复，测试代码质量（testifylint/thelper/usetesting）25→0，frpc 进程生命周期真 bug（进程组击杀）、全仓 go test -race 6 类数据竞争（含 1 个生产竞争）、SPDX license 头补齐 131 文件、前端测试套件 next-intl 迁移后 44 失败→全绿、过期 swagger 文档重新生成、pnpm-workspace 构建审批。

Experiments: #2-#17, #18, #20, #21, #23
Metric: total_issues 108 → 8 (-92.6%)

internal/apps/openflare/flared/routers.go

@@ -37,7 +37,11 @@ func PostHeartbeat(c *gin.Context) {
 		response.AbortUnauthorized(c, errTunnelTokenInvalid)
 		return
 	}
-	node := authNode.(*model.OpenFlareNode)
+	node, ok := authNode.(*model.OpenFlareNode)
+	if !ok {
+		response.AbortUnauthorized(c, errTunnelTokenInvalid)
+		return
+	}
 
 	result, err := Heartbeat(c.Request.Context(), node, payload)
 	if apiutil.AbortBadRequestOnError(c, err) {
@@ -63,7 +67,11 @@ func GetActiveConfig(c *gin.Context) {
 		response.AbortUnauthorized(c, errTunnelTokenInvalid)
 		return
 	}
-	node := authNode.(*model.OpenFlareNode)
+	node, ok := authNode.(*model.OpenFlareNode)
+	if !ok {
+		response.AbortUnauthorized(c, errTunnelTokenInvalid)
+		return
+	}
 
 	config, err := GetTunnelConfig(c.Request.Context(), node)
 	if apiutil.AbortBadRequestOnError(c, err) {
@@ -91,7 +99,9 @@ func PostApplyLog(c *gin.Context) {
 		return
 	}
 	if authNode, ok := c.Get(ctxFlaredNodeKey); ok {
-		payload.NodeID = authNode.(*model.OpenFlareNode).NodeID
+		if node, ok := authNode.(*model.OpenFlareNode); ok {
+			payload.NodeID = node.NodeID
+		}
 	}
 
 	log, err := ReportApplyLog(c.Request.Context(), payload)
@@ -115,6 +125,10 @@ func GetWebSocket(c *gin.Context) {
 		response.AbortUnauthorized(c, errTunnelTokenInvalid)
 		return
 	}
-	node := authNode.(*model.OpenFlareNode)
+	node, ok := authNode.(*model.OpenFlareNode)
+	if !ok {
+		response.AbortUnauthorized(c, errTunnelTokenInvalid)
+		return
+	}
 	ofws.ServeFlared(c, node.NodeID)
 }