ci(release): remove the daily release cron; dispatch-only

Releases are now triggered deliberately via workflow_dispatch. The
schedule produced a year of unattended runs stuck awaiting environment
approval, every real release was manually dispatched anyway, and two
runs on the same UTC day collide on the date-based tag. Rename the
workflow to "Release" accordingly and update RELEASING.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AViME1R9ES2UXT1uQDx1TG

.github/workflows/release.yml

@@ -1,9 +1,7 @@
-name: Automatic Release Creation
+name: Release
 
 on:
   workflow_dispatch:
-  schedule:
-    - cron: '0 10 * * *'
 
 jobs:
   create-metadata: