feat: audit vocabulary/term/authority creation, attributing the acting user (#21)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/db/src/seed.rs

@@ -5,7 +5,9 @@
 //! populated by the organization or a later import. The inventory-minimum fields
 //! (object number, name, location, …) live in the typed object core, not here.
 
-use domain::{AuthorityKind, FieldType, LocalizedLabel, NewFieldDefinition, VocabularyId};
+use domain::{
+    AuditActor, AuthorityKind, FieldType, LocalizedLabel, NewFieldDefinition, VocabularyId,
+};
 
 use crate::{fields, vocab};
 
@@ -119,7 +121,11 @@ async fn ensure_vocabulary(
     if let Some(existing) = vocab::vocabulary_by_key(&mut *conn, key).await? {
         Ok(existing.id)
     } else {
-        Ok(vocab::create_vocabulary(&mut *conn, key).await?.id)
+        Ok(
+            vocab::create_vocabulary(&mut *conn, AuditActor::System, key)
+                .await?
+                .id,
+        )
     }
 }