ci(docker): retry apk add in Dockerfile.database for apk.cgr.dev flakes

Mirror the retry-loop pattern from #28888 (which fixed backend/Dockerfile,
gateway/Dockerfile, and migrations/Dockerfile) into docker/Dockerfile.database.
The build_docker_database_image CI job has been intermittently failing with
"remote server returned error (try 'apk update')" when apk.cgr.dev flakes
mid-fetch; bumping the wolfi-base SHA doesn't address the mirror, only a
retry does.

Same explicit-failure form as #28888: exit non-zero on the 3rd miss instead
of silently succeeding because `sleep 5` was the last command in the
`&& break || sleep 5` chain.

docker/Dockerfile.database

@@ -15,16 +15,20 @@ USER root
 COPY --from=uvbin /uv /usr/local/bin/uv
 COPY --from=uvbin /uvx /usr/local/bin/uvx
 
-RUN apk add --no-cache \
-    bash \
-    gcc \
-    python3 \
-    python3-dev \
-    openssl \
-    openssl-dev \
-    nodejs \
-    npm \
-    libsndfile
+RUN for i in 1 2 3; do \
+      apk add --no-cache \
+        bash \
+        gcc \
+        python3 \
+        python3-dev \
+        openssl \
+        openssl-dev \
+        nodejs \
+        npm \
+        libsndfile && break; \
+      [ $i = 3 ] && { echo "apk add failed after 3 retries" >&2; exit 1; }; \
+      sleep 5; \
+    done
 
 ENV UV_PROJECT_ENVIRONMENT=/app/.venv \
     UV_LINK_MODE=copy \
@@ -66,7 +70,11 @@ FROM $LITELLM_RUNTIME_IMAGE AS runtime
 
 USER root
 
-RUN apk add --no-cache bash openssl tzdata nodejs npm python3 libsndfile && \
+RUN for i in 1 2 3; do \
+      apk add --no-cache bash openssl tzdata nodejs npm python3 libsndfile && break; \
+      [ $i = 3 ] && { echo "apk add failed after 3 retries" >&2; exit 1; }; \
+      sleep 5; \
+    done && \
     npm install -g npm@11.12.1 tar@7.5.11 glob@11.1.0 @isaacs/brace-expansion@5.0.1 minimatch@10.2.4 diff@8.0.3 && \
     GLOBAL="$(npm root -g)" && \
     find "$GLOBAL/npm" -type d -name "tar" -path "*/node_modules/tar" | while read d; do \