fix(runner): v5 - Job 層級 mutex 確保嚴格序列執行

根因確認:
- 即使有 needs 依賴，Jobs 仍可能在 "Set up job" 階段並行
- 所有 Jobs 共用同一 Runner，並行寫入 _diag/pages 造成衝突

永久解決方案:
- 每個 Job 加上 concurrency.group: runner-awoooi-cd-mutex
- cancel-in-progress: false (等待而非取消)
- 確保同一時間只有一個 Job 在 Runner 上執行

影響:
- CD 會變慢 (Jobs 嚴格序列)
- 但保證穩定性 (不再有檔案衝突)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/cd.yaml

@@ -57,6 +57,11 @@ jobs:
     name: "Pre-flight Check"
     runs-on: [self-hosted, harbor, k8s]
     timeout-minutes: 1
+    # 2026-03-29: Runner 全局 mutex，確保同一 Runner 不會並行執行任何 CD Job
+    # 使用固定 group 名稱 (非 run_id)，所有 CD Jobs 共用同一把鎖
+    concurrency:
+      group: runner-awoooi-cd-mutex
+      cancel-in-progress: false
     steps:
       # =======================================================================
       # 2026-03-29: Runner _diag/pages 檔案衝突修復 (v3)
@@ -130,6 +135,9 @@ jobs:
     runs-on: [self-hosted, harbor, k8s]
     needs: pre-flight-check
     timeout-minutes: 1
+    concurrency:
+      group: runner-awoooi-cd-mutex
+      cancel-in-progress: false
     outputs:
       api: ${{ inputs.force_deploy == true && 'true' || steps.filter.outputs.api }}
       web: ${{ inputs.force_deploy == true && 'true' || steps.filter.outputs.web }}
@@ -168,7 +176,10 @@ jobs:
     name: "Build API"
     runs-on: [self-hosted, harbor, k8s]
     needs: detect-changes
-    timeout-minutes: 20  # 2026-03-29: 增加超時時間 (Docker Build 需要更長時間)
+    timeout-minutes: 20
+    concurrency:
+      group: runner-awoooi-cd-mutex
+      cancel-in-progress: false
     if: |
       !inputs.skip_api && (
         needs.detect-changes.outputs.api == 'true' ||
@@ -208,7 +219,10 @@ jobs:
     name: "Build Web"
     runs-on: [self-hosted, harbor, k8s]
     needs: detect-changes
-    timeout-minutes: 20  # 2026-03-29: 增加超時時間 (Next.js Build 需要更長時間)
+    timeout-minutes: 20
+    concurrency:
+      group: runner-awoooi-cd-mutex
+      cancel-in-progress: false
     if: |
       !inputs.skip_web && (
         needs.detect-changes.outputs.web == 'true' ||
@@ -261,6 +275,9 @@ jobs:
     runs-on: [self-hosted, harbor, k8s]
     needs: [detect-changes, build-api, build-web]
     timeout-minutes: 10
+    concurrency:
+      group: runner-awoooi-cd-mutex
+      cancel-in-progress: false
     if: always() && (needs.build-api.result == 'success' || needs.build-api.result == 'skipped') && (needs.build-web.result == 'success' || needs.build-web.result == 'skipped')
     environment: production
     steps: