feat(deploy): SemVer 版本管理 + 自动化发版流水线

- deploy.yml: tag 触发（v*.*.*），四阶段调脚本（compile/test/release/deploy）
- manual.yml: workflow_dispatch 支持手动回滚，checkout 指定 tag
- scripts/ci/compile.sh: 构建 Go 二进制 + Flutter Web，打包 dist/
- scripts/ci/test.sh: go test + flutter analyze
- scripts/ci/release.sh: 解析 CHANGELOG.md → 更新 version.yaml → 创建 Forgejo Release
- scripts/ci/deploy.sh: 从 Release 下载产物（自动/手动均可）→ 部署到 EC2
- CHANGELOG.md: Keep a Changelog 格式，初始 v1.0.0 条目
- backend: GetRelease 改读 version.yaml，移除 ENV 变量依赖
- backend/config/version.yaml: 重置为 v1.0.0
- web/download.html: 动态拉取 /api/v1/public/release 展示版本号和更新内容

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/ci/test.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# test.sh  —  run backend and frontend checks
+set -euo pipefail
+
+export PATH="/opt/homebrew/bin:$PATH"
+export GOPROXY="${GOPROXY:-https://goproxy.cn,direct}"
+export PUB_HOSTED_URL="${PUB_HOSTED_URL:-https://pub.flutter-io.cn}"
+export FLUTTER_STORAGE_BASE_URL="${FLUTTER_STORAGE_BASE_URL:-https://storage.flutter-io.cn}"
+
+echo "==> test: go test"
+cd backend
+go test ./...
+cd ..
+
+echo "==> test: flutter analyze"
+cd client
+flutter analyze
+cd ..
+
+echo "==> test: done"