chore(ci): drop push-to-main publish trigger — dispatch-only (#91)

The push trigger fired on every release-PR squash-merge to main,
attempting to publish a version that workflow_dispatch on the prep
branch had already published — producing a 400 "node version already
exists" failure and a cosmetic red badge on the merge commit. With
the dispatch-from-prep-branch flow now standard (per CLAUDE.md and
releasing.md), the push trigger is redundant.

Updates docs/maintainers/releasing.md to match: drops the stale
"trade-off" callout (whose premise was the auto-publish on merge),
replaces the two anti-patterns whose rationale was the auto-trigger
with a single "don't forget to dispatch" reminder.

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

.github/workflows/publish.yml

@@ -1,12 +1,6 @@
 name: Publish to Comfy registry
 on:
   workflow_dispatch:
-  push:
-    branches:
-      - main
-      - master
-    paths:
-      - "pyproject.toml"
 
 permissions:
   issues: write