feat: media duplicate purge, part 1 of 3: persisted purge settings and the purge API

internal/infrastructure/persistence/models/purgeSettingsModel.go

@@ -0,0 +1,13 @@
+package models
+
+import "time"
+
+type PurgeSettings struct {
+	ID                       uint32 `gorm:"primaryKey"`
+	AutoPurgeEnabled         bool   `gorm:"not null"`
+	AutoPurgeIntervalDays    int    `gorm:"not null"`
+	LastPurgeAt              *time.Time
+	LastPurgeMerged          int `gorm:"not null"`
+	LastPurgeArticlesUpdated int `gorm:"not null"`
+	EnabledAt                *time.Time
+}