docs: eleven -> thirteen plugins in tagline

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: yves-vogl

build.py

@@ -31,7 +31,7 @@
 ORG = "basilica-audio"
 
 SITE_NAME = "Basilica Audio"
-SITE_TAGLINE = "Eleven sacred-architecture DSP plugins for heavy music"
+SITE_TAGLINE = "Thirteen sacred-architecture DSP plugins for heavy music"
 
 IMAGE_EXTS = {".png", ".jpg", ".jpeg", ".webp", ".gif"}
 AUDIO_EXTS = {".mp3", ".wav", ".ogg", ".flac", ".m4a"}