feat(caldav): implement service discovery for CalDAV with redirection

server/index.js

@@ -79,6 +79,21 @@ async function start() {
   app.use('/api/federation', calendarRoutes);
   app.get('/.well-known/redlight', wellKnownHandler);
 
+  // ── CalDAV service discovery (RFC 6764) ──────────────────────────────────
+  // Clients probe /.well-known/caldav then PROPFIND / before they know the
+  // real CalDAV mount point.  Redirect them to /caldav/ for all HTTP methods.
+  app.all('/.well-known/caldav', (req, res) => {
+    res.redirect(301, '/caldav/');
+  });
+  // Some clients (e.g. Thunderbird) send PROPFIND / directly at the server root.
+  // Express doesn't register non-standard methods, so intercept via middleware.
+  app.use('/', (req, res, next) => {
+    if (req.method === 'PROPFIND' && req.path === '/') {
+      return res.redirect(301, '/caldav/');
+    }
+    next();
+  });
+
   // Serve static files in production
   if (process.env.NODE_ENV === 'production') {
     app.use(express.static(path.join(__dirname, '..', 'dist')));