[chore] 自動化週發布：weekly-release-pr workflow

.github/workflows/weekly-release-pr.yml

@@ -0,0 +1,97 @@
+name: Weekly Release PR
+
+on:
+  schedule:
+    # 週六 10:00 UTC+8 = 週六 02:00 UTC
+    - cron: "0 2 * * 6"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pull-requests: write
+  actions: write
+
+jobs:
+  create-release-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check if develop is ahead of main
+        id: check
+        run: |
+          git fetch origin main develop
+          COMMITS_AHEAD=$(git rev-list --count origin/main..origin/develop)
+          echo "commits_ahead=$COMMITS_AHEAD" >> "$GITHUB_OUTPUT"
+          echo "develop is $COMMITS_AHEAD commits ahead of main"
+
+      - name: Skip if nothing to release
+        if: steps.check.outputs.commits_ahead == '0'
+        run: echo "develop is up to date with main, skipping."
+
+      # 以下 step 全由 if: 條件守衛，不依賴上方 skip step 的 exit 狀態
+      - name: Check for existing open release PR
+        if: steps.check.outputs.commits_ahead != '0'
+        id: existing
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          EXISTING=$(gh pr list --base main --head develop --state open --json number --jq '.[0].number // ""')
+          echo "existing_pr=$EXISTING" >> "$GITHUB_OUTPUT"
+          if [ -n "$EXISTING" ]; then
+            echo "Release PR #$EXISTING already open, skipping."
+          fi
+
+      - name: Create release PR
+        if: steps.check.outputs.commits_ahead != '0' && steps.existing.outputs.existing_pr == ''
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          DATE=$(TZ=Asia/Taipei date +%Y-%m-%d)
+          COMMITS_AHEAD=${{ steps.check.outputs.commits_ahead }}
+          cat > /tmp/release-pr-body.md <<EOF
+          ## Weekly Release — $DATE
+
+          Auto-generated by weekly-release-pr workflow.
+
+          **Commits ahead:** $COMMITS_AHEAD
+
+          ## Scope 對齊
+
+          - Source of truth: develop release promotion on $DATE.
+          - Depends on PR: none
+
+          Backend contract already in develop:
+          - [x] yes
+          - [ ] no
+
+          If no, this PR is:
+          - [ ] stacked on dependency branch
+          - [ ] intentionally blocked until dependency merges
+
+          ## 本 PR 明確不做
+
+          - 不新增任何程式碼變更，僅將 develop promote 到 main。
+          - 不修改任何未在 develop 上的內容。
+
+          ## Checklist
+
+          - [ ] CI 通過（CI 由 workflow dispatch 觸發，請到 Actions tab 查看結果，不會顯示在此 PR 的 Checks tab）
+          - [ ] 確認無 half-finished feature
+          - [ ] Merge
+
+          > Note: weekly-release-pr workflow 的 schedule / workflow_dispatch 需等此 workflow 檔案存在於 default branch（main）後才會啟用。
+          EOF
+          gh pr create \
+            --base main \
+            --head develop \
+            --title "[release] develop → main ($DATE)" \
+            --body-file /tmp/release-pr-body.md
+
+      - name: Dispatch CI against develop
+        if: steps.check.outputs.commits_ahead != '0' && steps.existing.outputs.existing_pr == ''
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: gh workflow run ci.yml --ref develop

scripts/pr-metadata-check.sh

@@ -221,7 +221,7 @@ main() {
   fi
 
   local depends_on_raw=""
-  depends_on_raw=$(grep -iE '^[[:space:]-]*Depends on PR[：:][[:space:]]*' "$body_file" | head -n1 | sed -E 's/^[^：:]*[：:][[:space:]]*//' | sed 's/[[:space:]]*$//')
+  depends_on_raw=$(grep -iE '^[[:space:]-]*Depends on PR[：:][[:space:]]*' "$body_file" | head -n1 | sed -E 's/^[^：:]*[：:][[:space:]]*//' | sed 's/[[:space:]]*$//' || true)
 
   if [ "$is_infra_or_chore" -eq 0 ] && [ "$is_release_promotion" -eq 0 ]; then
     grep -Eq '#[0-9]+' "$body_file" || failures+=("PR body 必須引用至少一個 issue 或 PR 編號，例如 #123")