fix: 修正 logo 中 N 和 G 字母造型

N 添加对角线笔画（█▄ █），G 添加内横杠（█ ▀█），
避免与 O 字母造型雷同。同步更新 ui.ts 中的硬编码 wordmark。

packages/server/src/groups/health.ts

@@ -0,0 +1,14 @@
+import { Schema } from "effect"
+import { HttpApiEndpoint, HttpApiGroup, OpenApi } from "effect/unstable/httpapi"
+
+export const HealthGroup = HttpApiGroup.make("server.health").add(
+  HttpApiEndpoint.get("health.get", "/api/health", {
+    success: Schema.Struct({ healthy: Schema.Literal(true) }),
+  }).annotateMerge(
+    OpenApi.annotations({
+      identifier: "v2.health.get",
+      summary: "Check server health",
+      description: "Check whether the API server is ready to accept requests.",
+    }),
+  ),
+)