CI: build on all branches, push only on master

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011sNqP1fsSPcDjcmLhWjNmD

Author: claude

.github/workflows/docker.yml

@@ -4,7 +4,6 @@ on:
   workflow_dispatch:
 
   push:
-    branches: ["master"]
 
   schedule:
     - cron: "0 8 * * 1"
@@ -48,6 +47,7 @@ jobs:
       image: "dockette/php"
       tag: "${{ matrix.item }}"
       context: "${{ matrix.item }}"
+      push: ${{ github.ref == 'refs/heads/master' }}
     strategy:
       matrix:
         include: