feat: add AI settings controls

tests/ai-routes.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, test } from "bun:test";
+import {
+	getAiDisabledMessage,
+	isAdminAiEnabled,
+	isAiFlagEnabled,
+	isClientAiEnabled,
+} from "@/lib/ai-feature-flags";
+
+describe("AI feature flags", () => {
+	test("AI admin flag defaults to enabled when unset", () => {
+		expect(isAdminAiEnabled({})).toBe(true);
+	});
+
+	test("AI admin flag disables routes when explicitly false", () => {
+		expect(isAdminAiEnabled({ AI_ENABLED: "false" })).toBe(false);
+		expect(isAdminAiEnabled({ AI_ENABLED: "0" })).toBe(false);
+	});
+
+	test("AI client flag follows NEXT_PUBLIC_AI_ENABLED before server fallback", () => {
+		expect(
+			isClientAiEnabled({ NEXT_PUBLIC_AI_ENABLED: "false", AI_ENABLED: "true" }),
+		).toBe(false);
+	});
+
+	test("truthy and falsy parsing remains explicit and predictable", () => {
+		expect(isAiFlagEnabled("yes")).toBe(true);
+		expect(isAiFlagEnabled("off")).toBe(false);
+		expect(isAiFlagEnabled("unexpected-value")).toBe(true);
+	});
+
+	test("disabled message explains the admin-controlled state", () => {
+		expect(getAiDisabledMessage().toLowerCase()).toContain("disabled");
+		expect(getAiDisabledMessage().toLowerCase()).toContain("administrator");
+	});
+});