fix: remove container spec, let runner provide Node.js and Docker

Runner v12.6.4 defaults to node:lts image which includes Node.js.
The explicit container block prevented Docker socket access needed
for image builds.

.forgejo/workflows/build-deploy.yml

@@ -16,8 +16,6 @@ concurrency:
 jobs:
   build:
     runs-on: ubuntu-latest
-    container:
-      image: node:22-bookworm
     steps:
       - name: Checkout code
         uses: actions/checkout@v6