Fix rowcolors bleeding into chord tabulars

Reset \rowcolors after the TOC longtable to prevent alternating
gray backgrounds from affecting leadsheets' chord placement
tabulars, which was clipping/overlaying song lyrics.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

songbook-style.sty

@@ -158,6 +158,7 @@
   \endhead
   \InputIfFileExists{\jobname.songtoc}{}{}%
   \end{longtable}%
+  \rowcolors{1}{}{}%
 }
 
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