fix(ci): isolate tenant dependency cache

Dockerfile.tenant

@@ -8,10 +8,9 @@ COPY yarn.lock ./yarn.lock
 COPY tenant-platform/package.json ./tenant-platform/package.json
 COPY docs-site/package.json ./docs-site/package.json
 
-ENV YARN_CACHE_FOLDER=/var/cache/yarn
-
-RUN --mount=type=cache,target=/var/cache/yarn,sharing=locked \
-    yarn install --frozen-lockfile
+# 依赖层本身会随 manifests/lockfile 缓存。禁止跨构建复用 Yarn 全局缓存：
+# 内部仓库一旦出现同版本制品被重新上传，共享缓存会保留旧字节并与锁文件摘要冲突。
+RUN yarn install --frozen-lockfile
 
 # GIT_COMMIT invalidates source-code layers on every commit, without re-running yarn install
 ARG GIT_COMMIT=unknown