server: Go 服务器（REST+WSS 网关+JWT+Argon2+配对+素材直链+任务状态机）；修复并发下线 send-on-closed-channel、下发查询 SQL 优先级、配对码原子占用、上传体积上限、JWT 默认密钥告警

server/internal/ws/key.go

@@ -0,0 +1,30 @@
+package ws
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"encoding/hex"
+	"os"
+	"path/filepath"
+)
+
+// LoadOrCreateServerKey 加载/生成服务器 Ed25519 密钥（hex 文件）
+func LoadOrCreateServerKey(path string) (ed25519.PrivateKey, error) {
+	if raw, err := os.ReadFile(path); err == nil {
+		seed, err := hex.DecodeString(string(raw))
+		if err == nil && len(seed) == ed25519.SeedSize {
+			return ed25519.NewKeyFromSeed(seed), nil
+		}
+	}
+	_, priv, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		return nil, err
+	}
+	if err = os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return nil, err
+	}
+	if err = os.WriteFile(path, []byte(hex.EncodeToString(priv.Seed())), 0o600); err != nil {
+		return nil, err
+	}
+	return priv, nil
+}