修复凭证测试器计数器、消除panic、补齐i18n

- credential_tester: testCredentialWithRetry返回ErrorType，修复网络错误计数器永久不递增的bug
- scanner: os.Exit(1)改为return，defer Cleanup可正常执行
- probe_parser: 5处panic改为error返回，调用链透传到init()
- common库: parsers/initialize/network/session共17处硬编码中文改用i18n
- services插件: 18个文件115处硬编码中文改用i18n
- locale: 补齐service/parser/network相关~25个中英文键

plugins/services/findnet.go

@@ -15,6 +15,7 @@ import (
 	"unicode"
 
 	"github.com/shadow1ng/fscan/common"
+	"github.com/shadow1ng/fscan/common/i18n"
 	"github.com/shadow1ng/fscan/plugins"
 )
 
@@ -45,7 +46,7 @@ func (p *FindNetPlugin) Scan(ctx context.Context, info *common.HostInfo, session
 		return &ScanResult{
 			Success: false,
 			Service: "findnet",
-			Error:   fmt.Errorf("FindNet插件仅支持RPC端口135"),
+			Error:   fmt.Errorf(i18n.Tr("service_port_restriction", "FindNet", "135")),
 		}
 	}
 
@@ -54,7 +55,7 @@ func (p *FindNetPlugin) Scan(ctx context.Context, info *common.HostInfo, session
 		return &ScanResult{
 			Success: false,
 			Service: "findnet",
-			Error:   fmt.Errorf("连接RPC端口失败: %w", err),
+			Error:   fmt.Errorf(i18n.Tr("service_conn_port_failed", "%w"), err),
 		}
 	}
 	defer func() { _ = conn.Close() }()