fix(welcome): 欢迎页沿用站点外观与 SEO 标题

合并 #683：欢迎页沿用站点外观与 SEO 标题

web/src/main.tsx

@@ -7,8 +7,10 @@ import { isIsolatedPrevisRepro } from "@/lib/dev-repro";
 installChunkRecovery();
 
 // The public film entry checks its availability independently of workspace bootstrap.
-if (/^\/welcome\/?$/.test(window.location.pathname)) void import("./welcome-application");
-else {
+if (/^\/welcome\/?$/.test(window.location.pathname)) {
+    void bootstrapAppearance().catch(() => undefined);
+    void import("./welcome-application");
+} else {
     // The backend-free DEV lab must not make requests before AppProviders isolates it.
     const appearanceReady = isIsolatedPrevisRepro(import.meta.env.DEV, window.location.pathname) ? Promise.resolve() : bootstrapAppearance();
     void import("./application");

web/src/pages/welcome/index.tsx

@@ -59,7 +59,6 @@ function WelcomeExperience({ look, brandName, onLookChange }: { look: WelcomeLoo
     const videoRef = useRef<HTMLVideoElement>(null);
 
     useEffect(() => {
-        document.title = "影策 · 让一个故事从文字走向银幕";
         const media = window.matchMedia("(prefers-reduced-motion: reduce)");
         const onMotion = () => setReduced(media.matches);
         media.addEventListener("change", onMotion);

web/test/welcome-title.test.mjs

@@ -0,0 +1,44 @@
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { test } from "node:test";
+import vm from "node:vm";
+
+const source = (path) => readFileSync(new URL(path, import.meta.url), "utf8");
+
+test("welcome entry loads configured appearance", async () => {
+    let calls = 0;
+    const imports = [];
+    const main = source("../src/main.tsx")
+        .replace(/^import .*;\n/gm, "")
+        .replace(/import\.meta\.env\.DEV/g, "false")
+        .replace(/import\(/g, "loadModule(");
+    vm.runInNewContext(main, {
+        window: { location: { pathname: "/welcome" } },
+        installChunkRecovery() {},
+        isIsolatedDirectorRepro: () => false,
+        bootstrapAppearance: async () => { calls++; },
+        loadModule: async (name) => { imports.push(name); },
+    });
+    await Promise.resolve();
+    assert.equal(calls, 1, "welcome entry must bootstrap appearance");
+    assert.deepEqual(imports, ["./welcome-application"]);
+});
+
+test("welcome effects preserve configured SEO title", () => {
+    const page = source("../src/pages/welcome/index.tsx");
+    // Run the actual mount effects with inert motion/scroll listeners.
+    const effects = [...page.matchAll(/useEffect\(\(\) => \{([\s\S]*?)\n    \}, \[([^\]]*)\]\);/g)].filter((match) => match[2] === "");
+    assert.ok(effects.length > 0);
+    for (const title of ["Custom SEO Title", "Custom Site Name"]) {
+        const document = { title };
+        for (const [, body] of effects) {
+            vm.runInNewContext(`(() => {${body}\n})()`, {
+                document,
+                window: { matchMedia: () => ({ matches: false, addEventListener() {}, removeEventListener() {} }), addEventListener() {}, removeEventListener() {} },
+                storyRef: { current: null }, restorePickerFocus: { current: false },
+                setReduced() {}, setLook() {}, getWelcomeLook() {},
+            });
+        }
+        assert.equal(document.title, title, "welcome must preserve appearance metadata title");
+    }
+});