fix(daemon): gate dolt-backup patrol behind darwin check

The dolt-backup patrol uses iCloud Drive for offsite sync, which only
exists on macOS. On Linux this generates HIGH priority escalation spam
every ~15 minutes. Gate behind runtime.GOOS == "darwin".

Based on PR #3041 (quad341) — extracted the 3-line fix from a larger
kitchen-sink PR.

Co-Authored-By: quad341 <noreply@users.github.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

internal/daemon/dolt_backup.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"time"
 
@@ -32,6 +33,11 @@ func doltBackupInterval(config *DaemonPatrolConfig) time.Duration {
 // syncDoltBackups syncs each production database to its configured backup location.
 // Non-fatal: errors are logged but don't stop the daemon.
 func (d *Daemon) syncDoltBackups() {
+	// Dolt backup uses iCloud Drive for offsite sync — only available on macOS.
+	// On Linux this generates HIGH priority escalation spam every ~15 minutes.
+	if runtime.GOOS != "darwin" {
+		return
+	}
 	if !IsPatrolEnabled(d.patrolConfig, "dolt_backup") {
 		return
 	}