feat(userscript): stamp and filter by kind in the manga script

userscript/test/logic.test.js

@@ -60,6 +60,7 @@ const {
   kagane,
   anchorsFromHTML,
   statusOf,
+  kindOf,
 } = require("../manga-bookmark.user.js");
 
 // detect() reads only these four properties off location.
@@ -377,3 +378,17 @@ test("statusOf defaults a missing status to reading", () => {
   assert.equal(statusOf({ status: "archived" }), "archived");
   assert.equal(statusOf({ status: "finished" }), "finished");
 });
+
+// ============================================================
+// kindOf — a row written before the kind column existed has none, and every
+// one of those is manga.
+// ============================================================
+
+test("kindOf defaults a missing kind to manga", () => {
+  assert.equal(kindOf({}), "manga");
+  assert.equal(kindOf({ kind: "" }), "manga");
+});
+
+test("kindOf passes through an explicit kind", () => {
+  assert.equal(kindOf({ kind: "novel" }), "novel");
+});