fix(ai-toolbar): gate paste capture on AI availability

tests/ai-toolbar.test.ts

@@ -323,6 +323,19 @@ describe("Keyboard shortcuts – toolbar integration contract", () => {
 	});
 });
 
+describe("Global paste capture – AI availability gate", () => {
+	test("document-level paste handlers only arm when AI is actually usable", () => {
+		const source = readToolbarSource();
+
+		expect(source).toContain(
+			"if (!isAuthenticated || isPending || !canUseAi || aiLoading) return;",
+		);
+		expect(source).toContain(
+			"}, [isAuthenticated, isPending, canUseAi, aiLoading]);",
+		);
+	});
+});
+
 // ─── Cycle 8: Multi-image thumbnail strip ────────────────────────────────────
 //
 // When multiple images are attached, they render as a horizontal scrollable