chore: Update copyright year from 2025 to 2026 across core files

- Updated copyright headers in 3,055 core application files
- Changed 'Copyright (C) 2014-2025' to 'Copyright (C) 2014-2026'
- Added 123 new files from EspoCRM core updates
- Removed 4 deprecated files
- Total changes: 61,637 insertions, 54,283 deletions

This is a routine maintenance update for the new year 2026.

application/Espo/Resources/i18n/en_US/Export.json

@@ -11,7 +11,7 @@
     "options": {
         "format": {
             "csv": "CSV",
-            "xlsx": "XLSX (Excel)"
+            "xlsx": "XLSX · Spreadsheet"
         },
         "status": {
             "Pending": "Pending",