feat: 顶栏显示后端应用版本号

后端 /api/health 返回 BuildVersion(由 ldflags 注入的 main.version),
前端顶栏设置按钮左侧展示 v<版本>。

web/src/app/(main)/_components/main-content.tsx

@@ -1,11 +1,12 @@
 "use client";
 
-import type { ReactNode } from "react";
+import { type ReactNode, useEffect, useState } from "react";
 
 import { usePathname } from "next/navigation";
 
 import { Separator } from "@/components/ui/separator";
 import { SidebarTrigger } from "@/components/ui/sidebar";
+import { api } from "@/lib/api";
 import { cn } from "@/lib/utils";
 import { useCurrentUser } from "@/hooks/use-current-user";
 
@@ -29,6 +30,14 @@ function isFullBleed(pathname: string) {
 export function MainContent({ children }: { children: ReactNode }) {
   const currentUser = useCurrentUser();
   const pathname = usePathname();
+  const [version, setVersion] = useState("");
+
+  useEffect(() => {
+    api
+      .health()
+      .then((h) => setVersion(h.version ?? ""))
+      .catch(() => setVersion(""));
+  }, []);
 
   if (isFullBleed(pathname)) {
     return <>{children}</>;
@@ -52,6 +61,9 @@ export function MainContent({ children }: { children: ReactNode }) {
             <SearchDialog />
           </div>
           <div className="flex items-center gap-2">
+            {version && (
+              <span className="text-muted-foreground text-xs font-medium tabular-nums">版本·v{version}</span>
+            )}
             <LayoutControls />
             <ThemeSwitcher />
             <AccountSwitcher users={[currentUser]} />

web/src/lib/api.ts

@@ -99,6 +99,9 @@ const arr = <T>(x: T[] | null | undefined): T[] => x ?? [];
 const tq = (task?: string, sep: "?" | "&" = "?") => (task ? `${sep}task=${encodeURIComponent(task)}` : "");
 
 export const api = {
+  // 后端应用版本号（release 时由 ldflags 注入，默认 "dev"）。
+  health: () => get<{ ok: boolean; service: string; version: string }>("/health"),
+
   // ---- auth ----
   authStatus: () => get<{ initialized: boolean }>("/auth/status"),
   login: (username: string, password: string) =>