ci: build the backend image in its own workflow and shorten the panel offer wait [CI]

.woodpecker/dev-backend-image.yml

@@ -0,0 +1,46 @@
+labels:
+  ci: domain-linux-native
+  platform: linux/amd64
+
+clone:
+  - name: git
+    image: plugin-git
+    settings:
+      lfs: false
+      # 要拿到 tag 才算得出开发版本号（ci/version.sh：自最近 tag 的提交数）
+      tags: true
+
+when:
+  - event: push
+    branch: main
+    evaluate: 'CI_COMMIT_MESSAGE contains "[CI]"'
+
+# 后端镜像：和 dev-image.yml（Agent 镜像）并行，各自的 restore 只还原自己要用的依赖。构建好之后、推送之前由 ci/wait-for-checks.sh 等 verify 和 web-build。
+# 前端用 web-build workflow 的产物（ci/shared-web.sh）。
+
+concurrency: 1
+
+steps:
+  - name: restore-linux-dependencies
+    image: bash
+    environment:
+      NUGET_PACKAGES: /home/justme/woodpecker/cache/nuget/packages
+    commands:
+      - python3 ci/guard-step.py restore-backend-dependencies 1800 bash ci/restore-linux-dependencies.sh dev-backend
+    depends_on: []
+
+  - name: build-linux-amd64-backend
+    image: bash
+    environment:
+      NUGET_PACKAGES: /home/justme/woodpecker/cache/nuget/packages
+      ZOT_REGISTRY: registry.oeo.one
+      ZOT_USERNAME: justme
+      ZOT_SECRET:
+        from_secret: zot_secret
+      RELEASE_API_URL: https://mo.oeo.one
+      RELEASE_SIGNING_KEY:
+        from_secret: release_signing_key
+    commands:
+      - python3 ci/guard-step.py build-linux-amd64-backend 1800 bash ci/build-dev-image.sh backend
+    depends_on:
+      - restore-linux-dependencies

.woodpecker/dev-image.yml

@@ -15,8 +15,10 @@ when:
     branch: main
     evaluate: 'CI_COMMIT_MESSAGE contains "[CI]"'
 
+# Agent 镜像：三个 RID 的 Agent 构建，构建完发布。后端镜像在 dev-backend-image.yml 里并行构建：Woodpecker 一个 workflow 里的步骤按依赖深度分层，
+# 下一层要等上一层全部结束，发布放在后端构建（最慢）后面会白等。
 # 镜像构建和 verify（后端快速测试）、web-build 并行跑，不再等它们：构建好之后、推送之前由 ci/wait-for-checks.sh 等这两个 workflow 都成功
-# （任何一个失败就不推；提交信息写 [SKIP TESTS] 只跳过后端测试，verify 照样是成功）。机器有 6 个 workflow 槽（WOODPECKER_MAX_WORKFLOWS），三个同时跑放得下。
+# （任何一个失败就不推；提交信息写 [SKIP TESTS] 只跳过后端测试，verify 照样是成功）。机器有 6 个 workflow 槽（WOODPECKER_MAX_WORKFLOWS），四个同时跑放得下。
 
 concurrency: 1
 
@@ -26,25 +28,9 @@ steps:
     environment:
       NUGET_PACKAGES: /home/justme/woodpecker/cache/nuget/packages
     commands:
-      - python3 ci/guard-step.py restore-linux-dependencies 3600 bash ci/restore-linux-dependencies.sh dev
+      - python3 ci/guard-step.py restore-linux-dependencies 3600 bash ci/restore-linux-dependencies.sh dev-agent
     depends_on: []
 
-  - name: build-linux-amd64-backend
-    image: bash
-    environment:
-      NUGET_PACKAGES: /home/justme/woodpecker/cache/nuget/packages
-      ZOT_REGISTRY: registry.oeo.one
-      ZOT_USERNAME: justme
-      ZOT_SECRET:
-        from_secret: zot_secret
-      RELEASE_API_URL: https://mo.oeo.one
-      RELEASE_SIGNING_KEY:
-        from_secret: release_signing_key
-    commands:
-      - python3 ci/guard-step.py build-linux-amd64-backend 1800 bash ci/build-dev-image.sh backend
-    depends_on:
-      - restore-linux-dependencies
-
   - name: build-arm64-agent-musl
     image: bash
     environment: