chore: reduce scheduled build from daily to weekly on Thursdays

Thursday chosen to avoid build failures needing attention on the
busiest days of the working week.

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

Author: boite

.github/workflows/production.yml

@@ -6,7 +6,7 @@ on:
     branches:
     - master
   schedule:
-  - cron: 00 4 * * *
+  - cron: 00 4 * * 4
 
 jobs:
   build: