chore: restore Dockerfile to upstream v0.1.110

Reverting Dockerfile to match upstream version:
- Use golang:1.26.2-alpine instead of 1.25
- Use Alpine as final runtime image (not Debian)
- Remove LS binary and certificate setup
- Restore apk-based package management
- Remove multi-architecture build targets

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

Dockerfile

@@ -7,9 +7,8 @@
 # =============================================================================
 
 ARG NODE_IMAGE=node:24-alpine
-ARG GOLANG_IMAGE=golang:1.25-alpine
+ARG GOLANG_IMAGE=golang:1.26.2-alpine
 ARG ALPINE_IMAGE=alpine:3.21
-ARG DEBIAN_IMAGE=debian:bookworm-slim
 ARG POSTGRES_IMAGE=postgres:18-alpine
 ARG GOPROXY=https://goproxy.cn,direct
 ARG GOSUMDB=sum.golang.google.cn
@@ -64,12 +63,10 @@ COPY --from=frontend-builder /app/backend/internal/web/dist ./internal/web/dist
 
 # Build the binary (BuildType=release for CI builds, embed frontend)
 # Version precedence: build arg VERSION > cmd/server/VERSION
-ARG TARGETARCH
-ARG TARGETOS=linux
 RUN VERSION_VALUE="${VERSION}" && \
     if [ -z "${VERSION_VALUE}" ]; then VERSION_VALUE="$(tr -d '\r\n' < ./cmd/server/VERSION)"; fi && \
     DATE_VALUE="${DATE:-$(date -u +%Y-%m-%dT%H:%M:%SZ)}" && \
-    CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build \
+    CGO_ENABLED=0 GOOS=linux go build \
     -tags embed \
     -ldflags="-s -w -X main.Version=${VERSION_VALUE} -X main.Commit=${COMMIT} -X main.Date=${DATE_VALUE} -X main.BuildType=release" \
     -trimpath \
@@ -82,9 +79,9 @@ RUN VERSION_VALUE="${VERSION}" && \
 FROM ${POSTGRES_IMAGE} AS pg-client
 
 # -----------------------------------------------------------------------------
-# Stage 4: Final Runtime Image (Debian for glibc — LS binary requires it)
+# Stage 4: Final Runtime Image
 # -----------------------------------------------------------------------------
-FROM ${DEBIAN_IMAGE}
+FROM ${ALPINE_IMAGE}
 
 # Labels
 LABEL maintainer="Wei-Shaw <github.com/Wei-Shaw>"
@@ -92,25 +89,27 @@ LABEL description="Sub2API - AI API Gateway Platform"
 LABEL org.opencontainers.image.source="https://github.com/Wei-Shaw/sub2api"
 
 # Install runtime dependencies
-RUN apt-get update && apt-get install -y --no-install-recommends \
+RUN apk add --no-cache \
     ca-certificates \
-    curl \
-    wget \
-    gosu \
-    proxychains4 \
     tzdata \
-    libpq5 \
+    su-exec \
-    && rm -rf /var/lib/apt/lists/*
+    libpq \
+    zstd-libs \
+    lz4-libs \
+    krb5-libs \
+    libldap \
+    libedit \
+    && rm -rf /var/cache/apk/*
 
 # Copy pg_dump and psql from the same postgres image used in docker-compose
+# This ensures version consistency between backup tools and the database server
 COPY --from=pg-client /usr/local/bin/pg_dump /usr/local/bin/pg_dump
 COPY --from=pg-client /usr/local/bin/psql /usr/local/bin/psql
 COPY --from=pg-client /usr/local/lib/libpq.so.5* /usr/local/lib/
-RUN ldconfig
 
 # Create non-root user
-RUN groupadd -g 1000 sub2api && \
+RUN addgroup -g 1000 sub2api && \
-    useradd -u 1000 -g sub2api -m -s /bin/sh sub2api
+    adduser -u 1000 -G sub2api -s /bin/sh -D sub2api
 
 # Set working directory
 WORKDIR /app
@@ -119,21 +118,6 @@ WORKDIR /app
 COPY --from=backend-builder --chown=sub2api:sub2api /app/sub2api /app/sub2api
 COPY --from=backend-builder --chown=sub2api:sub2api /app/backend/resources /app/resources
 
-# Copy Language Server binary and cert (for LS pool mode)
-# Enable with: ANTIGRAVITY_LS_MODE=true ANTIGRAVITY_APP_ROOT=/app/ls
-# TARGETARCH is set automatically by buildx (amd64 or arm64)
-ARG TARGETARCH
-COPY --chown=sub2api:sub2api deploy/ls-bin/language_server_linux_* /tmp/ls-bin/
-COPY --chown=sub2api:sub2api deploy/ls-bin/cert.pem /app/ls/extensions/antigravity/dist/languageServer/
-RUN mkdir -p /app/ls/extensions/antigravity/bin && \
-    if [ "$TARGETARCH" = "arm64" ]; then \
-    cp /tmp/ls-bin/language_server_linux_arm /app/ls/extensions/antigravity/bin/language_server_linux_arm; \
-    else \
-    cp /tmp/ls-bin/language_server_linux_x64 /app/ls/extensions/antigravity/bin/language_server_linux_x64; \
-    fi && \
-    chmod +x /app/ls/extensions/antigravity/bin/language_server_linux_* && \
-    rm -rf /tmp/ls-bin
-
 # Create data directory
 RUN mkdir -p /app/data && chown sub2api:sub2api /app/data