✨ feat(db): 数据库连接新增 SOCKS5/HTTP 代理能力并兼容 SRV/SSH 场景

- 后端 ConnectionConfig 增加代理配置并完成规范化处理
- 普通 TCP 数据源通过本地转发接入代理
- MongoDB 使用 Dialer 支持代理连接（含 SRV）
- 前端连接配置新增代理 UI、字段清洗与数据回填
- refs #122

internal/proxy/proxy_test.go

@@ -0,0 +1,44 @@
+package proxy
+
+import (
+	"strings"
+	"testing"
+
+	"GoNavi-Wails/internal/connection"
+)
+
+func TestNormalizeConfigSupportsSocks5hAlias(t *testing.T) {
+	cfg, err := NormalizeConfig(connection.ProxyConfig{
+		Type: "SOCKS5H",
+		Host: "127.0.0.1",
+		Port: 1080,
+	})
+	if err != nil {
+		t.Fatalf("NormalizeConfig returned error: %v", err)
+	}
+	if cfg.Type != "socks5" {
+		t.Fatalf("expected normalized proxy type socks5, got %s", cfg.Type)
+	}
+}
+
+func TestForwarderCacheKeyIncludesCredentialFingerprint(t *testing.T) {
+	base := connection.ProxyConfig{
+		Type:     "socks5",
+		Host:     "127.0.0.1",
+		Port:     1080,
+		User:     "tester",
+		Password: "first-password",
+	}
+	other := base
+	other.Password = "second-password"
+
+	keyA := forwarderCacheKey(base, "db.internal", 3306)
+	keyB := forwarderCacheKey(other, "db.internal", 3306)
+
+	if keyA == keyB {
+		t.Fatalf("expected different cache key for different credentials")
+	}
+	if strings.Contains(keyA, base.Password) || strings.Contains(keyB, other.Password) {
+		t.Fatalf("cache key should not contain raw password")
+	}
+}