feat: sync embedded analytics theme with parent app

lib/theme-sync.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, test } from "bun:test";
+import { resolveIncomingThemeMode, resolveStoredTheme } from "./theme-sync";
+
+describe("theme sync helpers", () => {
+  test("resolves stored analytics theme values", () => {
+    expect(resolveStoredTheme("light", true)).toBe("light");
+    expect(resolveStoredTheme("dark", false)).toBe("dark");
+    expect(resolveStoredTheme("system", true)).toBe("dark");
+    expect(resolveStoredTheme("system", false)).toBe("light");
+  });
+
+  test("maps new-api theme messages to analytics themes", () => {
+    expect(resolveIncomingThemeMode("light", true)).toBe("light");
+    expect(resolveIncomingThemeMode("dark", false)).toBe("dark");
+    expect(resolveIncomingThemeMode("auto", true)).toBe("dark");
+    expect(resolveIncomingThemeMode("auto", false)).toBe("light");
+    expect(resolveIncomingThemeMode("system", true)).toBe("dark");
+    expect(resolveIncomingThemeMode("unknown", true)).toBeNull();
+  });
+});