1.3.1 – i18n fixes and complete .pot file

What's changed

• Fixed 3 hardcoded strings in the debug log section that were not wrapped in yourls__(): Debug Log, Clear log, and the parenthetical note about the log file
• Populated languages/yourls-change-notifier.pot with all 105 translatable strings — the file was previously empty (header only), making it impossible to produce translations