test: rename workflows to .yml and gate downstream on prepare success

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/print1.yml

@@ -9,6 +9,7 @@ on:
 jobs:
   print:
     runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     steps:
       - name: 每 10 秒打印一次数字
         run: |

.gitea/workflows/print2.yml

@@ -9,6 +9,7 @@ on:
 jobs:
   print:
     runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
     steps:
       - name: 每 10 秒打印一次数字
         run: |