chore: set up 'next' prerelease channel for dogfooding

- add channels.next (preid rc, @next dist-tag) to .bumpy/_config.json
- add next to the release workflow push triggers
- make the release concurrency group per-branch

Author: theoephraim

.bumpy/_config.json

@@ -12,5 +12,10 @@
   "publish": {
     "provenance": true,
     "npmStaged": true
+  },
+  // prerelease channel — dogfooding our own feature: pushes to `next` publish
+  // `-rc.N` versions to the @next dist-tag (prerelease versions are never committed)
+  "channels": {
+    "next": { "branch": "next", "preid": "rc", "tag": "next" }
   }
 }

.github/workflows/release.yaml

@@ -8,10 +8,11 @@
 name: Release
 on:
   push:
-    branches: [main]
+    branches: [main, next] # `next` = prerelease channel (dogfooding bumpy's own feature)
 
 concurrency:
-  group: bumpy-release
+  # per-branch so a `next` prerelease run doesn't queue behind a `main` stable run
+  group: bumpy-release-${{ github.ref }}
   cancel-in-progress: false
 
 jobs: