fix(create): prevent duplicate rapid submissions

web/test/creation-submit-gate.test.ts

@@ -0,0 +1,14 @@
+import { expect, test } from "bun:test";
+
+import { createCreationSubmitGate } from "../src/pages/create/creation-submit-gate";
+
+test("creation submit gate rejects a second submit until the first submit releases it", () => {
+    const gate = createCreationSubmitGate();
+
+    expect(gate.tryAcquire()).toBe(true);
+    expect(gate.tryAcquire()).toBe(false);
+
+    gate.release();
+
+    expect(gate.tryAcquire()).toBe(true);
+});