Fix note sync reliability and Unicode filename support

- Fixed critical bug where notes with empty category had malformed IDs (leading slash)
- Added URL encoding for Czech and Unicode characters in WebDAV paths
- Fixed filename sanitization to preserve Unicode characters (only remove filesystem-unsafe chars)
- Updated note preview to show first non-empty line after title instead of repeating title
- Adjusted default column widths for better proportions (increased window width to 1300px)
- Protection mechanism now works correctly with proper note ID matching

src/components/NotesList.tsx

@@ -125,9 +125,17 @@ export function NotesList({
   };
 
   const getPreview = (content: string) => {
-    // grab first 100 characters of note's content, remove markdown syntax from the preview
-    const previewContent = content.substring(0, 100);
-    const cleanedPreview = previewContent.replace(/[#*`]/g, '');
+    // Skip first line (title) and find first non-empty line
+    const lines = content.split('\n');
+    const contentLines = lines.slice(1); // Skip first line
+    
+    // Find first non-empty line
+    const firstContentLine = contentLines.find(line => line.trim().length > 0);
+    if (!firstContentLine) return '';
+    
+    // Take up to 100 characters from the content lines
+    const previewContent = contentLines.join(' ').substring(0, 100);
+    const cleanedPreview = previewContent.replace(/[#*`]/g, '').trim();
     return cleanedPreview;
   };
 
@@ -160,7 +168,7 @@ export function NotesList({
     <div 
       ref={containerRef}
       className="bg-gray-50 dark:bg-gray-900 border-r border-gray-200 dark:border-gray-700 flex flex-col relative flex-shrink-0"
-      style={{ width: `${width}px`, minWidth: '240px', maxWidth: '600px' }}
+      style={{ width: `${width}px`, minWidth: '340px', maxWidth: '600px' }}
     >
       <div className="p-4 border-b border-gray-200 dark:border-gray-700">
         <div className="flex items-center justify-between mb-3">