Language-aware house style and a resizable chat split

House style now follows the app language: Chinese UI forces the new
bundled humanizer-zh skill into every run, English forces humanizer -
one variant per run, picked by preference with cross-language fallback
so an older catalogue never silently loses house style. Both variants
are protected from grant/revoke, list_skills labels each with its
language, the bundle guard requires both, and startup sync imports the
new skill into existing orgs on next launch. Covered by a unit test
that flips app_state.language and asserts which humanizer compiles.

The chat split is now adjustable: drag the conversation list's right
edge (200-480px, persisted in localStorage) and the composer textarea
grew a native vertical resize grip capped at 40vh.

tests/e2e/builtin-skills-fixture.ts

@@ -14,6 +14,12 @@ export function seedBuiltinSkillsFixture(root: string): string {
     "---\nname: humanizer\nversion: 2.1.1\ndescription: |\n  Remove signs of AI-generated writing from text.\n---\n\nWrite like a person.\n",
     "utf8",
   );
+  mkdirSync(join(root, "Humanizer-zh"), { recursive: true });
+  writeFileSync(
+    join(root, "Humanizer-zh", "SKILL.md"),
+    "---\nname: humanizer-zh\nversion: 1.0.0\ndescription: |\n  去除文本中的 AI 生成痕迹。\n---\n\n像真人一样写作。\n",
+    "utf8",
+  );
   mkdirSync(join(root, "engineering"), { recursive: true });
   writeFileSync(
     join(root, "engineering", "engineering-backend-architect.md"),

tests/e2e/desktop.spec.ts

@@ -182,7 +182,7 @@ test("onboards, hires, and creates work in the Electron shell", async () => {
       const result = await api.loadSnapshot() as { ok: true; data: { skillDefinitions: Array<{ slug: string }> } };
       return result.data.skillDefinitions.map((skill) => skill.slug).sort();
     });
-    expect(skillSlugs).toEqual(["engineering-backend-architect", "humanizer"]);
+    expect(skillSlugs).toEqual(["engineering-backend-architect", "humanizer", "humanizer-zh"]);
 
     // The global pause toggle lives in the topbar on every page.
     const pauseToggle = page.getByRole("button", { name: "Pause agents" });