Add admin config page and runtime-tunable upload/rate-limit settings

internal/config/repository.go

@@ -0,0 +1,40 @@
+package config
+
+import "gorm.io/gorm"
+
+type Repository struct {
+	db *gorm.DB
+}
+
+func NewRepository(db *gorm.DB) *Repository {
+	return &Repository{db: db}
+}
+
+func (r *Repository) Get(key string) (*ConfigEntry, error) {
+	var e ConfigEntry
+	if err := r.db.First(&e, "key = ?", key).Error; err != nil {
+		return nil, err
+	}
+	return &e, nil
+}
+
+func (r *Repository) Upsert(key, value string) error {
+	// Prefer a simple approach that works across sqlite/postgres/mysql.
+	// Try update first, then insert if nothing updated.
+	res := r.db.Model(&ConfigEntry{}).Where("key = ?", key).Update("value", value)
+	if res.Error != nil {
+		return res.Error
+	}
+	if res.RowsAffected > 0 {
+		return nil
+	}
+	return r.db.Create(&ConfigEntry{Key: key, Value: value}).Error
+}
+
+func (r *Repository) List() ([]ConfigEntry, error) {
+	var entries []ConfigEntry
+	if err := r.db.Order("key asc").Find(&entries).Error; err != nil {
+		return nil, err
+	}
+	return entries, nil
+}