Initial commit: docker-compose-updater

Go 项目，包含：
- 服务端 updater：两阶段协议，ECDSA 签名验证，AES-GCM 加密
- 发送端 dcu-send：Gitea Action CLI
- internal/auth：加解密/签名/会话管理
- internal/docker：Docker CLI 容器查找/拉取/重建
- action/：Gitea Action 定义
- deploy/Dockerfile：多阶段构建
- .gitea/workflows/build.yaml：CI/CD

action/Dockerfile

@@ -0,0 +1,11 @@
+FROM golang:1.25-alpine AS builder
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /dcu-send ./cmd/dcu-send
+
+FROM alpine:3.20
+RUN apk add --no-cache ca-certificates tzdata
+COPY --from=builder /dcu-send /usr/local/bin/dcu-send
+ENTRYPOINT ["dcu-send"]

action/action.yml

@@ -0,0 +1,34 @@
+name: Docker Compose Updater
+description: 触发远程 docker-compose 服务更新（拉取/重启）
+author: docker-compose-updater
+branding:
+  icon: refresh-cw
+  color: blue
+
+inputs:
+  url:
+    description: Updater 地址，如 https://updater.example.com
+    required: true
+  project:
+    description: docker-compose 项目名
+    required: true
+  service:
+    description: 要操作的 service 名（api、frontend 等）
+    required: true
+  action:
+    description: '操作类型: update(拉取+重启) / pull(仅拉取) / restart(仅重启)'
+    required: false
+    default: update
+  signing_key:
+    description: ECDSA 签名私钥 PEM 内容（Gitea Secret）
+    required: true
+
+runs:
+  using: docker
+  image: Dockerfile
+  env:
+    SIGNING_KEY: ${{ inputs.signing_key }}
+    UPDATER_URL: ${{ inputs.url }}
+    UPDATER_PROJECT: ${{ inputs.project }}
+    UPDATER_SERVICE: ${{ inputs.service }}
+    UPDATER_ACTION: ${{ inputs.action }}