Add search_whole_words toggle to the viewer. When enabled, the
search pattern is wrapped in \b boundaries to match only whole
words. Accessible via Search F9 menu → Whole words.
- Viewer::search_whole_words: bool field (default false)
- search() method wraps pattern in r"\b{}\b" when enabled
- ToggleWholeWords in ViewerCmd + Search menu entry
- execute_menubar_cmd dispatches the toggle
Added 1 unit test verifying 4 matches without whole-words
(foo, food, barefoot, foo) vs 2 with whole-words (foo, foo).
Tests: 1424 pass (was 1423), zero warnings.
vasilito
ab2798834c