Add config loading and dry-run validation

internal/config/config.go

@@ -1,3 +1,70 @@
 package config
 
-type Config struct{}
+type Config struct {
+	Pipelines []Pipeline `yaml:"pipelines"`
+}
+
+type Pipeline struct {
+	ID           string           `yaml:"id"`
+	Source       Backend          `yaml:"source"`
+	Validation   ValidationPolicy `yaml:"validation"`
+	Destinations []Destination    `yaml:"destinations"`
+}
+
+type Destination struct {
+	ID        string         `yaml:"id"`
+	Backend   string         `yaml:"backend"`
+	Path      string         `yaml:"path"`
+	URI       string         `yaml:"uri"`
+	Endpoint  string         `yaml:"endpoint"`
+	Bucket    string         `yaml:"bucket"`
+	Prefix    string         `yaml:"prefix"`
+	Region    string         `yaml:"region"`
+	ForcePath bool           `yaml:"force_path_style"`
+	Creds     Credentials    `yaml:"credentials"`
+	Publish   *PublishPolicy `yaml:"publish"`
+	Transform Transform      `yaml:"transform"`
+	Transfer  TransferPolicy `yaml:"transfer"`
+}
+
+type Backend struct {
+	Backend   string      `yaml:"backend"`
+	Path      string      `yaml:"path"`
+	URI       string      `yaml:"uri"`
+	Endpoint  string      `yaml:"endpoint"`
+	Bucket    string      `yaml:"bucket"`
+	Prefix    string      `yaml:"prefix"`
+	Region    string      `yaml:"region"`
+	ForcePath bool        `yaml:"force_path_style"`
+	Creds     Credentials `yaml:"credentials"`
+}
+
+type Credentials struct {
+	AccessKeyIDEnv     string `yaml:"access_key_id_env"`
+	SecretAccessKeyEnv string `yaml:"secret_access_key_env"`
+}
+
+type ValidationPolicy struct {
+	OnDigestMismatch string `yaml:"on_digest_mismatch"`
+}
+
+type PublishPolicy struct {
+	Source bool `yaml:"source"`
+	HTML   bool `yaml:"html"`
+}
+
+type Transform struct {
+	MarkdownToHTML *MarkdownToHTML `yaml:"markdown_to_html"`
+}
+
+type MarkdownToHTML struct {
+	Enabled bool   `yaml:"enabled"`
+	Mode    string `yaml:"mode"`
+}
+
+type TransferPolicy struct {
+	OnDestinationSame  string `yaml:"on_destination_same"`
+	OnDestinationOlder string `yaml:"on_destination_older"`
+	OnDestinationNewer string `yaml:"on_destination_newer"`
+	OnConflict         string `yaml:"on_conflict"`
+}