v1.3.0

Added

• Undo button displays the number of available undo levels — text changes to
  "Undo (N)" and the tooltip explains how many rename batches can be reverted
• Case-transform modifier in replacement field tokens: = (unchanged), -
  (lower), + (upper), ! (capitalise first char), * (Title Case)
• Centre-align (^) in replacement field tokens
• Toolbar-state and preview-delay persistence in Settings
• tools/po_check.py: PO file inspection tool using the babel library
  (statistics, untranslated entries, regex search, language diff) — replaces
  ad-hoc grep/msgfmt usage that breaks on multi-line entries
• src/pbrenamer/argparse_qt.py: add_qt_arguments() declares Qt CLI flags
  (--style, --platform, …) as a proper argparse argument group; collected in
  args.qt_args as single-dash tokens ready for QApplication; Qt options are
  hidden from the usage: line to reduce noise while remaining fully visible in
  the --help output
• tools/fix_po_files.py: utility to normalise PO file formatting in bulk
• Comprehensive test suite covering all source modules at 100%; includes the
  full main window (_on_preview, _refresh_conflicts, context menus, undo,
  conflict detection, drag-and-drop, keyboard shortcuts, settings dialog,
  file-info window, pattern-help dialog, presets, bookmarks, i18n bootstrap,
  and all core modules)
• Headless Qt test execution via QT_QPA_PLATFORM=offscreen in conftest.py;
  QMenu.exec patched at module level so no blocking dialog appears during CI
  or local make test runs

Changed

• main() now uses parse_args() instead of parse_known_args(); unknown
  flags are rejected natively by argparse — _validate_qt_argv removed

Fixed

• {L} search-pattern token now matches Unicode letters; accented Latin
  (é, ê, ü, …), Cyrillic, Greek and all other Unicode letter categories
  are captured correctly — was limited to ASCII [a-zA-Z], now uses
  [^\W\d_] which covers all \w characters that are neither digits nor
  underscores
• Qt built-in translations are now loaded alongside the application catalogue
  so dialog buttons (OK, Cancel, Yes, No, …) are correctly translated
  when a non-English language is selected
• Pattern help dialog: HTML-escaped {1:<12} so the browser no longer
  interprets <12> as an HTML tag
• Fifteen # pragma: no cover guards on reachable logic replaced by targeted
  tests: case-insensitive no-match in rename_using_plain_text, zero-width
  regex guard, {newnum} CLI branch (start value, invalid start, no-match,
  field error, collision k+=1), rename failure exit path, main() headless
  dispatch, _parse_exif_datetime on malformed input, _read_iptc unknown
  key, _apply_case unknown modifier