Move cache env vars to workflow level, remove debug step

Move PNPM_STORE_DIR and COREPACK_HOME to workflow-level env
which may propagate differently than job-level in act_runner.

.gitea/workflows/deploy-preview.yaml

@@ -4,12 +4,13 @@ on:
   pull_request:
     types: [opened, synchronize, reopened]
 
+env:
+  PNPM_STORE_DIR: /pnpm-store
+  COREPACK_HOME: /pnpm-store/.corepack
+
 jobs:
   deploy:
     runs-on: ubuntu-latest
-    env:
-      PNPM_STORE_DIR: /pnpm-store
-      COREPACK_HOME: /pnpm-store/.corepack
     steps:
       - uses: actions/checkout@v4