fix(cd): disable buildkit on host runner

.gitea/workflows/cd.yaml

@@ -341,11 +341,11 @@ jobs:
       # ── API 鏡像建置（含 Layer Cache 加速）──────────────────────────────
       # 2026-04-01 ogt: CACHE_BUST=git_sha 確保 src/ 和 models.json 層每次重建
       # deps 層 (pip install) 仍可 cache → 加速；代碼/配置層強制失效
-      # 首席架構師 Review C1 (2026-04-05 Claude Code): 補 DOCKER_BUILDKIT=1
-      # BUILDKIT_INLINE_CACHE=1 只有在 BuildKit 啟用時才有效
+      # 2026-05-05 Codex: host runner docker-cli lacks buildx; keep BuildKit
+      # disabled until buildx is installed on the persistent runner image.
       - name: Build and Push API
         env:
-          DOCKER_BUILDKIT: "1"
+          DOCKER_BUILDKIT: "0"
         run: |
           docker build -f apps/api/Dockerfile \
             --build-arg BUILDKIT_INLINE_CACHE=1 \
@@ -364,10 +364,10 @@ jobs:
       # 2026-04-01 Claude Code: CACHE_BUST=git_sha 取代 --no-cache
       # - deps 層 (pnpm install) 仍可 cache → 節省 ~2-3 min
       # - COPY . . 以下由 CACHE_BUST 強制失效 → 業務邏輯/CSRF 等變更正確進入 bundle
-      # 2026-04-12 ogt: 實測 --no-cache=10m50s；CACHE_BUST=5m50s，恢復此方案
+      # 2026-05-05 Codex: mirror API build mode; host runner docker-cli lacks buildx.
       - name: Build and Push Web
         env:
-          DOCKER_BUILDKIT: "1"
+          DOCKER_BUILDKIT: "0"
         run: |
           docker build -f apps/web/Dockerfile \
             --build-arg NEXT_PUBLIC_API_URL=https://awoooi.wooo.work \