Refactor CLI to be a thin adapter over the library

- util/cli.go: RunMark() now maps CLI flags into mark.Config and
  delegates to mark.Run(); all core processing logic removed
- util/cli_test.go: absorb Test_setLogLevel from deleted main_test.go
- main.go, main_test.go: removed (entry point is now cmd/mark/main.go)
- Makefile: update build target to ./cmd/mark with -o mark

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

util/cli_test.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"testing"
 
+	"github.com/reconquest/pkg/log"
+	"github.com/stretchr/testify/assert"
 	"github.com/urfave/cli/v3"
 )
 
@@ -74,3 +76,44 @@ func TestContentAppearanceFlagValidation(t *testing.T) {
 		}
 	})
 }
+
+func Test_setLogLevel(t *testing.T) {
+type args struct {
+lvl string
+}
+tests := map[string]struct {
+args        args
+want        log.Level
+expectedErr string
+}{
+"invalid": {args: args{lvl: "INVALID"}, want: log.LevelInfo, expectedErr: "unknown log level: INVALID"},
+"empty":   {args: args{lvl: ""}, want: log.LevelInfo, expectedErr: "unknown log level: "},
+"info":    {args: args{lvl: log.LevelInfo.String()}, want: log.LevelInfo},
+"debug":   {args: args{lvl: log.LevelDebug.String()}, want: log.LevelDebug},
+"trace":   {args: args{lvl: log.LevelTrace.String()}, want: log.LevelTrace},
+"warning": {args: args{lvl: log.LevelWarning.String()}, want: log.LevelWarning},
+"error":   {args: args{lvl: log.LevelError.String()}, want: log.LevelError},
+"fatal":   {args: args{lvl: log.LevelFatal.String()}, want: log.LevelFatal},
+}
+for name, tt := range tests {
+t.Run(name, func(t *testing.T) {
+cmd := &cli.Command{
+Name: "test",
+Flags: []cli.Flag{
+&cli.StringFlag{
+Name:  "log-level",
+Value: tt.args.lvl,
+Usage: "set the log level. Possible values: TRACE, DEBUG, INFO, WARNING, ERROR, FATAL.",
+},
+},
+}
+err := SetLogLevel(cmd)
+if tt.expectedErr != "" {
+assert.EqualError(t, err, tt.expectedErr)
+} else {
+assert.NoError(t, err)
+assert.Equal(t, tt.want, log.GetLevel())
+}
+})
+}
+}