chore: add site_config collection to pb-init-v3.sh

scripts/pb-init-v3.sh

@@ -376,6 +376,13 @@ create "book_ratings" '{
     {"name":"rating",   "type":"number", "required":true}
   ]}'
 
+create "site_config" '{
+  "name":"site_config","type":"base","fields":[
+    {"name":"decoration",    "type":"text"},
+    {"name":"logoAnimation", "type":"text"},
+    {"name":"eventLabel",    "type":"text"}
+  ]}'
+
 # ── 5. Field migrations (idempotent — adds fields missing from older installs) ─
 add_field "scraping_tasks" "heartbeat_at"           "date"
 add_field "audio_jobs"     "heartbeat_at"           "date"