重构 monorepo 并完善网页端订阅与首页体验

- 迁移为 frontend-web、frontend-electron、backend-web 与 docker 部署结构
- 网页端：订阅门禁二次弹窗、套餐/支付组件化、顶栏分组对齐
- 首页：最近文件与模板库布局优化，缩略图对齐，下载与删除操作
- 新增管理后台、支付与云端文件 API，更新 README 与项目规范

Co-authored-by: Cursor <cursoragent@cursor.com>

docker/php/entrypoint-dev.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+set -e
+
+if ! php -m 2>/dev/null | grep -q pdo_mysql; then
+  echo "[api] installing pdo_mysql..."
+  apt-get update -qq
+  DEBIAN_FRONTEND=noninteractive apt-get install -y -qq --no-install-recommends \
+    libmariadb-dev-compat $PHPIZE_DEPS
+  docker-php-ext-install -j"$(nproc)" pdo_mysql
+  apt-get purge -y --auto-remove $PHPIZE_DEPS
+  rm -rf /var/lib/apt/lists/*
+fi
+
+host="${SOON_DB_HOST:-mysql}"
+port="${SOON_DB_PORT:-3306}"
+user="${SOON_DB_USER:-soondesign}"
+pass="${SOON_DB_PASS:-soondesign}"
+db="${SOON_DB_NAME:-soondesign}"
+
+i=0
+while [ "$i" -lt 60 ]; do
+  if php -r "
+    try {
+      new PDO(
+        'mysql:host=${host};port=${port};dbname=${db};charset=utf8mb4',
+        '${user}',
+        '${pass}',
+        [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
+      );
+      exit(0);
+    } catch (Throwable \$e) {
+      exit(1);
+    }
+  "; then
+    break
+  fi
+  i=$((i + 1))
+  sleep 2
+done
+
+php /docker/php/migrate-dev-schema.php || true
+php /docker/php/seed-dev-admin.php || true
+
+exec php -S 0.0.0.0:8080 -t /var/www/public /docker/php/router-dev.php