Allow targetting branch on alpha build

Author: satyakigh

.github/workflows/alpha-release.yml

@@ -5,6 +5,11 @@ on:
   schedule:
     - cron: '0 8 * * 1,3'  # Monday, Wednesday 8am
   workflow_dispatch:
+    inputs:
+      ref:
+        description: 'Branch, tag, or commit to build from'
+        required: false
+        default: 'main'
 
 jobs:
   create-alpha-tag:
@@ -16,7 +21,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
         with:
-          ref: 'main'
+          ref: ${{ inputs.ref || 'main' }}
           fetch-depth: 0
 
       - name: Configure Git