feat: add semantic CSS stylesheets (#3274)

Co-authored-by: Cursor Agent <cursoragent@cursor.com>

tests/e2e/specs/semantic-css/dormant-mode.spec.ts

@@ -0,0 +1,37 @@
+import { readSemanticCssFixture, updateSemanticCssFixture } from "../../fixtures/db";
+import { createSampleResumeFromDashboard, openSidebarSection } from "../../fixtures/resume";
+import { resumeIdFromPage } from "../../fixtures/semantic-css";
+import { expect, test } from "../../fixtures/test";
+
+test("@semantic-css keeps the legacy editor available while both flags are off", async ({
+	authPage: page,
+}, testInfo) => {
+	await createSampleResumeFromDashboard(page, testInfo);
+	await openSidebarSection(page, "Custom Styles");
+
+	await expect(page.getByLabel("Target Scope")).toBeVisible();
+	await expect(page.getByRole("textbox", { name: "Semantic CSS stylesheet" })).toHaveCount(0);
+});
+
+test("@semantic-css preserves a persisted stylesheet through an old-client resume update", async ({
+	authPage: page,
+}, testInfo) => {
+	await createSampleResumeFromDashboard(page, testInfo);
+	const resumeId = resumeIdFromPage(page);
+	const source = { languageVersion: 1, text: "@version 1;\nname { color: #dc2626; }\n" };
+	await updateSemanticCssFixture(resumeId, { stylesheet: { mode: "semantic", source, applied: source } });
+	await page.reload();
+
+	await openSidebarSection(page, "Basics");
+	await page.getByLabel("Headline").fill("Preserves semantic stylesheet");
+	await expect
+		.poll(() => readSemanticCssFixture(resumeId))
+		.toMatchObject({
+			headline: "Preserves semantic stylesheet",
+			stylesheet: {
+				mode: "semantic",
+				source,
+				applied: source,
+			},
+		});
+});