grammar-reader: pin every referent code (Person and Population arms survived mutation)

The Aetheria-written fixture binds only Faction, Cargo and Place, so mutants
deleting the Person and Population arms survived. The new test authors each
code at the role's key and reads it back as its own kind. Builds.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ghostlight/src/aetheria/tests.rs

@@ -353,3 +353,25 @@ fn reading_leaves_the_catalog_and_its_directory_untouched() {
     assert_eq!(std::fs::read(&path).unwrap(), bytes);
     assert_eq!(listing(dir.path()), before, "the reader created a file");
 }
+
+#[test]
+fn every_referent_code_maps_to_its_own_kind() {
+    // The fixture binds only Faction, Cargo and Place; Person and Population
+    // are authored here at the role's integer key, each read back as itself.
+    for (code, expected) in [
+        (1, GrammarReferentKind::Person),
+        (2, GrammarReferentKind::Faction),
+        (3, GrammarReferentKind::Population),
+        (4, GrammarReferentKind::Place),
+        (5, GrammarReferentKind::Cargo),
+    ] {
+        let mut rows = fixture_rows();
+        edit(&mut rows, "verb-attack", |cells| cells[3][0][2] = json!(code));
+        let catalog = read(&rows).unwrap();
+        assert_eq!(
+            catalog.grammar.verb("attack"),
+            Some(&verb(RenderPath::ShipAction, &[("target", expected)])),
+            "code {code}"
+        );
+    }
+}