refactor: update class names for consistency and improve styling

- Changed `flex-shrink-0` to `shrink-0` in multiple components for better consistency.
- Updated button and checkbox classes to use `rounded-sm` for a more uniform appearance.
- Adjusted backdrop blur classes for modals to `backdrop-blur-xs` for a subtler effect.
- Removed unused Tailwind CSS configuration file.

server/index.js

@@ -100,7 +100,7 @@ async function start() {
   // Serve static files in production
   if (process.env.NODE_ENV === 'production') {
     app.use(express.static(path.join(__dirname, '..', 'dist')));
-    app.get('*', (req, res) => {
+    app.get('/*splat', (req, res) => {
       res.sendFile(path.join(__dirname, '..', 'dist', 'index.html'));
     });
   }

server/routes/caldav.js

@@ -278,7 +278,7 @@ ${propXml}
 }
 
 // ── OPTIONS ────────────────────────────────────────────────────────────────
-router.options('*', (req, res) => {
+router.options('/*splat', (req, res) => {
   setDAVHeaders(res);
   res.status(200).end();
 });
@@ -529,7 +529,7 @@ router.delete('/:username/calendar/:filename', caldavAuth, validateCalDAVUser, a
 });
 
 // ── Fallback ───────────────────────────────────────────────────────────────
-router.all('*', caldavAuth, (req, res) => {
+router.all('/*splat', caldavAuth, (req, res) => {
   setDAVHeaders(res);
   res.status(405).end();
 });