ci: use GITHUB_TOKEN for semantic-release and add tag trigger to publish

- Switched from custom GH_TOKEN PAT to built-in GITHUB_TOKEN (always valid)
- Added push tags trigger (v*) to publish.yaml since GITHUB_TOKEN
  releases don't fire the 'on: release' event

.github/workflows/publish.yaml

@@ -1,6 +1,9 @@
 name: Publish Release
 
 on:
+  push:
+    tags:
+      - 'v*'
   release:
     types: [published]
   workflow_dispatch:

.github/workflows/release.yml

@@ -37,5 +37,5 @@ jobs:
 
       - name: Release
         env:
-          GITHUB_TOKEN: ${{ secrets.GH_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: npx semantic-release