OCR often merges adjacent words when spacing is tight, e.g.
"atmyschool" → "at my school", "goodidea" → "good idea".
New _try_split_merged_word() uses dynamic programming to find the
shortest sequence of dictionary words covering the token. Integrated
as step 5 in _spell_fix_token() after general spell correction.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
