Add app version number, shown in Navbar next to the logo

New backend/VERSION file (starts at 1.0.0) served via GET /api/version,
displayed as a small "v1.0.0" next to the StreamHoard wordmark. Going
forward I'll bump this on meaningful changes -- patch for fixes, minor
for new features, major for big/breaking redesigns.

frontend/src/components/Navbar.jsx

@@ -3,12 +3,14 @@ import { useAuth } from "../lib/auth";
 import { useProfile } from "../lib/profile";
 import { Search, LogOut, Upload, Settings as SettingsIcon } from "lucide-react";
 import { useState, useEffect } from "react";
+import api from "../lib/api";
 
 export const Navbar = () => {
   const { user, logout } = useAuth();
   const { active } = useProfile();
   const nav = useNavigate();
   const [scrolled, setScrolled] = useState(false);
+  const [version, setVersion] = useState("");
 
   useEffect(() => {
     const onScroll = () => setScrolled(window.scrollY > 20);
@@ -16,6 +18,10 @@ export const Navbar = () => {
     return () => window.removeEventListener("scroll", onScroll);
   }, []);
 
+  useEffect(() => {
+    api.get("/version").then(({ data }) => setVersion(data.version)).catch(() => {});
+  }, []);
+
   const linkClass = ({ isActive }) =>
     `text-sm tracking-wide transition-colors duration-300 ${isActive ? "text-white" : "text-[#8A8A8A] hover:text-white"}`;
 
@@ -26,6 +32,7 @@ export const Navbar = () => {
           <Link to="/browse" className="flex items-center gap-2" data-testid="nav-logo">
             <span className="font-display text-2xl font-black tracking-tighter text-white">StreamHoard</span>
             <span className="text-[#D9381E] text-2xl leading-none">.</span>
+            {version && <span className="text-[10px] text-[#8A8A8A] self-start mt-1" data-testid="nav-version">v{version}</span>}
           </Link>
           {user && (
             <nav className="hidden md:flex items-center gap-7">