Change podcast-data schedule to twice a month

The data update workflow previously ran three times a week (Monday,
Wednesday, Friday). The podcast data changes infrequently, so this
cadence produced more runs and generated commits than necessary.

Reduce it to twice a month — the 2nd and the 16th at 04:00 UTC — to
keep the generated content reasonably fresh while cutting noise.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: andygrunwald

.github/workflows/podcast-data.yml

@@ -6,7 +6,7 @@ on:
       - main
   workflow_dispatch:
   schedule:
-    - cron: "5 11 * * 1,3,5" # Run at 04:05 on Monday, Wednesday, and Friday.
+    - cron: "0 4 2,16 * *" # Run at 04:00 UTC on the 2nd and 16th of each month.
 
 jobs:
   data_workflow: