feat(webhook): add webhook client for RSVP and photo uploads

server/internal/config/config.go

@@ -15,6 +15,7 @@ type Config struct {
 	Storage StorageConfig `yaml:"storage"`
 	Email   EmailConfig   `yaml:"email"`
 	Upload  UploadConfig  `yaml:"upload"`
+	Webhook WebhookConfig `yaml:"webhook"`
 }
 
 type ServerConfig struct {
@@ -52,6 +53,17 @@ type UploadConfig struct {
 	MaxFiles  int `yaml:"max_files"`
 }
 
+// WebhookConfig is entirely optional: each URL is only called if set, so a
+// deployment can wire up RSVP notifications without touching photo uploads
+// (or either at all).
+type WebhookConfig struct {
+	RSVPURL        string            `yaml:"rsvp_url"`
+	PhotoURL       string            `yaml:"photo_url"`
+	Secret         string            `yaml:"secret"`  // signs the payload via HMAC-SHA256, sent in X-Webhook-Signature
+	Headers        map[string]string `yaml:"headers"` // extra headers sent with every webhook request, e.g. Authorization
+	TimeoutSeconds int               `yaml:"timeout_seconds"`
+}
+
 // Path resolves the config file location: $CONFIG_PATH, or ./config.yaml.
 func Path() string {
 	if p := os.Getenv("CONFIG_PATH"); p != "" {
@@ -83,6 +95,9 @@ func Load(path string) (*Config, error) {
 	if cfg.Upload.MaxFiles == 0 {
 		cfg.Upload.MaxFiles = 10
 	}
+	if cfg.Webhook.TimeoutSeconds == 0 {
+		cfg.Webhook.TimeoutSeconds = 5
+	}
 	if cfg.Wedding.Date.IsZero() {
 		return nil, fmt.Errorf("wedding.date is required in %s", path)
 	}