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

server/index.js

@@ -197,7 +197,7 @@ app.use(express.json({ limit: '64kb' })); // prevent oversized JSON payloads
 // Used by Docker HEALTHCHECK and orchestrators.
 // ---------------------------------------------------------------------------
 app.get('/health', (req, res) => {
-  res.json({ status: 'ok', uptime: process.uptime() });
+  res.json({ status: 'ok', uptime: process.uptime(), version });
 });
 
 app.get('/ready', (req, res) => {