feat(deploy): gencode 纳入 server 发版产物 + EC2 生码封装

server 流水线编译并发布 jiu-gencode 二进制（回滚路径随 release 资产
自动下载），部署到 /opt/jiu/backend/，对旧版回滚做存在性判断优雅跳过。
新增 deploy/jiu-gencode.sh 封装自动读 production.env，线上生码从此
一条 ssh 即可，无需本地交叉编译 + scp。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y2Wdwo7SmgBJU37cBrkhPK

scripts/ci/compile-backend.sh

@@ -13,10 +13,14 @@ echo "==> compile-backend: tag=${TAG}"
 # Build Go backend (linux/amd64 for EC2)
 cd backend
 GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -o jiu-server .
+# Platform code-minting CLI (gencode) ships alongside the server so codes can be
+# minted on EC2 without cross-compiling/scp each time.
+GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -o jiu-gencode ./cmd/gencode
 cd ..
 
 mkdir -p dist
 mv backend/jiu-server dist/jiu-server
+mv backend/jiu-gencode dist/jiu-gencode
 
 # Shared infrastructure (nginx/systemd/env/compose). version.yaml is NOT here —
 # it belongs to the client pipeline.
@@ -26,7 +30,8 @@ tar -czf dist/configs.tar.gz \
   deploy/production.env.template \
   deploy/setup-ec2.sh \
   deploy/docker-compose.yml \
-  deploy/docker-compose.jiu.yml
+  deploy/docker-compose.jiu.yml \
+  deploy/jiu-gencode.sh
 
 echo "==> compile-backend: done — dist/ contents:"
 ls -lh dist/