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-tauri/tauri.conf.json

@@ -13,9 +13,9 @@
     "windows": [
       {
         "title": "Nextcloud Notes",
-        "width": 1200,
+        "width": 1300,
         "height": 800,
-        "minWidth": 900,
+        "minWidth": 800,
         "minHeight": 600,
         "devtools": true
       }