API: Add const, func, and struct comments for easier troubleshooting

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/api/api_event.go

@@ -11,6 +11,7 @@ import (
 // Event represents an api event type.
 type Event string
 
+// Canonical event payload status strings used by the API layer.
 const (
 	StatusCreated Event = "created"
 	StatusUpdated Event = "updated"