feat: add version footer to dashboard UI (v1.2.1)

- /health endpoint now includes version field
- Footer displays 'sofarr vX.Y.Z' fetched on page load
- Subtle .app-version styling (smaller, dimmed)
- Bump version to 1.2.1, update CHANGELOG

public/app.js

@@ -27,13 +27,25 @@ document.addEventListener('DOMContentLoaded', () => {
   initThemeSwitcher();
   initTabs();
   initHistoryControls();
-  
+  loadAppVersion();
+
   document.getElementById('login-form').addEventListener('submit', handleLogin);
   document.getElementById('logout-btn').addEventListener('click', handleLogout);
   document.getElementById('show-all-toggle').addEventListener('change', handleShowAllToggle);
   document.getElementById('status-btn').addEventListener('click', toggleStatusPanel);
 });
 
+function loadAppVersion() {
+  fetch('/health')
+    .then(r => r.json())
+    .then(data => {
+      if (data.version) {
+        document.getElementById('app-version').textContent = `sofarr v${data.version}`;
+      }
+    })
+    .catch(() => {});
+}
+
 function initThemeSwitcher() {
   const saved = localStorage.getItem('sofarr-theme') || 'light';
   document.querySelectorAll('.theme-btn').forEach(btn => {